#internals-and-peps | Python | Page 41

wide shuttle May 18, 2020, 4:54 AM

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You're making a function anyway, one that's 3-5 lines. In one instance you just use lambda to make it, in the other def

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The latter has readability and gets debugging information, such as the function name bound the __repr__

rich wharf May 18, 2020, 4:54 AM

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if I made a def for each of these, I'd have to scroll up constantly

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and I've still kept them readable

wide shuttle May 18, 2020, 4:55 AM

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They both result in a callable object in memory with compiled code, and if you're making a 5 line lambda, a 5 line def at more or less the same place would be okay.

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Since it apparently doesn't matter if the function object goes out of scope.

rich wharf May 18, 2020, 4:55 AM

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the problem is I have a continuous list with each of those

raven ridge May 18, 2020, 4:56 AM

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you don't need to scroll up - you can def a new function right where you are lambda'ing a new function.

rich wharf May 18, 2020, 4:56 AM

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no I can't, not in the middle of a list

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defs aren't expressions

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these lists usually have a couple dozen lambdas in one place with simple logic

wide shuttle May 18, 2020, 4:57 AM

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I guess to each their preference. I just really hate the look of long expressions that have multiple lambda subexpressions in them

rich wharf May 18, 2020, 4:57 AM

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Statement(
            'builtins_forever',
            'Repeat the code forever',
            ['forever'],
            lt.function('frame, exprs', lambda v: (
                (yield from lt.during(lambda v: True, lambda v: (
                    yield from v.frame.execute(v.exprs[0])
                )))
            ))
        )```

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these lambdas are simple logic in a continuous list with items just like that

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so it's organized to have all of this data in one place for me

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this use case is rare but it does exactly what my needs are

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and this is a language that has code meant to be as easy as pseudo-code for basic scripting purposes that I'm making

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but it's convenient to have this all in one place with the function right there

wide shuttle May 18, 2020, 4:59 AM

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This less readable for me, as there is less information. I have to parse your expression to see what it does. To me, this is the kind of thing I don't like reading.

north root May 18, 2020, 4:59 AM

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i'm gonna be honest, that looks kind of horrifying to me in python. although, i guess it's just preference

rich wharf May 18, 2020, 4:59 AM

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to me it's just fine

wide shuttle May 18, 2020, 4:59 AM

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Having a function with an actual descriptive name and then using that descriptive name just looks so much better to me

rich wharf May 18, 2020, 5:00 AM

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then it'll be hundreds of lines above where that statement object is

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maybe it is preference, but I think I'm going to be keeping lambdas like that

wide shuttle May 18, 2020, 5:01 AM

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Yeah, maybe. I'm not saying that you shouldn't; I'm just saying that I've personally not reviewed a lot of code where more complicated lambda would have increased readability.

rich wharf May 18, 2020, 5:01 AM

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I only have a few functions that aren't anonymous like those ones, and those are for complex logic

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And you're right

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A somewhat logical lambda is uncommon but this is a use case for it

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And even though it's less readable then a regular function, it's still readable enough, and it's convenient because all of the expression is in one place

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And it means adding new statements is easy too

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All I have to do is add a statement in one place with one function attached

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And editing these statements is convenient too

wide shuttle May 18, 2020, 5:03 AM

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But you're calling for multi-expression lambdas, right? The ones that would take 3-5 statements.

rich wharf May 18, 2020, 5:03 AM

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Yes, but this is a good use case for me

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Usually I can use a regular function if it's only a few lines away

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In this case, it will never be a few lines away because of the sheer size of this

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This use case is very uncommon, but that's my point of view

primal girder May 18, 2020, 5:04 AM

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With a meaningful function name it doesn't matter how far away it is

rich wharf May 18, 2020, 5:04 AM

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The expression already has a name

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If it is this hard to debug, I can just attach the expression name to the lambda can't I?

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And it does matter how far away it is

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It's much harder to maintain when it's not all in one place

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If I wanted to translate all of the code with messages in it, I wouldn't have to go to two places to do this

primal girder May 18, 2020, 5:05 AM

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That's where good editors come in.

ionic void May 18, 2020, 5:05 AM

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Why does Python have so many ways to format strings? Doesn't Python try to do similar things in one way?

primal girder May 18, 2020, 5:06 AM

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They can take you directly to the implementation and back

wide shuttle May 18, 2020, 5:06 AM

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Hey @vital moon, I think #python-discussion is a better place for such questions

rich wharf May 18, 2020, 5:06 AM

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Honestly, this is just a matter of preference, but even then I like having it all in one spot.

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And having to constantly switch places even with an IDE doesn't seem like the solution I want

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I think that's enough explaining my case for now.

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Thanks for taking the time to make your counterarguments and reasoning.

north root May 18, 2020, 5:07 AM

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string concatenation and f-strings are pretty standard in many languages. str.format is there for backwards compatibility and is useful for templating strings. i think printf style is also for backwards compatibility.

rich wharf May 18, 2020, 5:08 AM

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my preference is the fstring

north root May 18, 2020, 5:08 AM

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yeah, i agree in that it's a matter of preference

wide shuttle May 18, 2020, 5:08 AM

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I think that having reasonable limitations on what you can and can't do is what has created a very readable language. It may be that those decisions are not the best for every case, but I think picking different defaults would lead to a less readable language in general, maybe just not in this particular use case.

ionic void May 18, 2020, 5:08 AM

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But why don't they remove the old ones?

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It's slower than f-strings.

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Is backwards compatibility the only reason?

rich wharf May 18, 2020, 5:09 AM

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Because it would break backwards compatibility

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If people update to the new version, they would have to rewrite plenty of code

ionic void May 18, 2020, 5:09 AM

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Oh, hm.

wide shuttle May 18, 2020, 5:09 AM

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Not entirely, you can do things with str.format that are not possible f-strings, such as formatting a string at a later point in time.

rich wharf May 18, 2020, 5:09 AM

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A lot of times that isn't worth it

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And that's true too

wide shuttle May 18, 2020, 5:10 AM

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But, it would break a lot and it's probably not worth it.

ionic void May 18, 2020, 5:10 AM

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Oh really!?

rich wharf May 18, 2020, 5:10 AM

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Actually yes, I use that too

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I have a list of template strings and I format them

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When is Python 4 coming, if it comes, out of curiousity?

ionic void May 18, 2020, 5:12 AM

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There's a Python 4 planned?

rich wharf May 18, 2020, 5:12 AM

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I don't think so yet

ionic void May 18, 2020, 5:12 AM

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Didn't Python 3 take like 10 years.

rich wharf May 18, 2020, 5:12 AM

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But I'm wondering if and when it will

ionic void May 18, 2020, 5:12 AM

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To fully roll out.

rich wharf May 18, 2020, 5:12 AM

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I'm not sure

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What was Python 1 like?

wide shuttle May 18, 2020, 5:14 AM

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There was a plan to just go to Python 4 after Python 3.9, but that has been abandoned a few years ago. The idea was to keep the transition small to avoid the Py2-Py3 controversy.

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However, there are sometimes some breaking changes that you do want to make and reserving a major version change for those kind of changes has its purpose as well

rich wharf May 18, 2020, 5:15 AM

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What would a Python 4 have that would break Python 3 compatibility?

wide shuttle May 18, 2020, 5:15 AM

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One change that was planned for a Py4 release was the new annotations behavior. I'm actually not sure when they want do that now. I think they may still wait for Py4 with that.

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It's what you get now if you do the from __future__ import annotations import

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I haven't kept up with that PEP, though, so maybe the planned release version has changed. (That PEP was released when Py4 was still planned as the version after P3.9)

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(It's this pep: https://www.python.org/dev/peps/pep-0563/)

rich wharf May 18, 2020, 5:18 AM

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If Python did add better lambdas, I'd propose syntax like this maybe (even though it has its downsides), but I don't think good lambdas are easy with Python's whitespace system

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doStuffWith(
  lambda: (
    if True:
      print(3)
    else:
      for i in range(3):
        print(i)
  ), lambda: (
    for i in range(3):
      if i == 2:
        print(i)
  )
)

ionic void May 18, 2020, 5:19 AM

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I never really understood how dunder name == dunder main helps check if a module is imported or not, does Python just magically add something?

rich wharf May 18, 2020, 5:19 AM

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__name__ is basically what is calling it

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if it's "__main__", it's the actual package and module

ionic void May 18, 2020, 5:19 AM

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But isn't Python a functional language?

rich wharf May 18, 2020, 5:19 AM

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if it's something else, like "mymod", I think that's the module importing it

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What do you mean?

north root May 18, 2020, 5:20 AM

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python is multi-paradigm

ionic void May 18, 2020, 5:20 AM

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and main is kind of like a method which is part of a class?

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Oh why did Discord do that.

rich wharf May 18, 2020, 5:20 AM

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__main__ is a builtin variable that gets set

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and it's markdown

ionic void May 18, 2020, 5:20 AM

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Oh so it is built-in

rich wharf May 18, 2020, 5:20 AM

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any variables starting with __ and ending with __ are python builtin variables and are reserved for internal use

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you can set them, but you shouldn't

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it's like how list = [1, 2, 3] is bad practice

ionic void May 18, 2020, 5:21 AM

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I'm always confused about what is or is not builtin to Python

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Got it

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Python has a lot more built-in functions

raven ridge May 18, 2020, 5:23 AM

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__all__ is an exception to that rule, at least - it's meant to be set by package owners

ionic void May 18, 2020, 5:23 AM

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that could be used without even importing libraries.

unkempt rock May 18, 2020, 5:23 AM

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its what makes python easier than everything else

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besides scratch

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hehe

ionic void May 18, 2020, 5:23 AM

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Oh haha

rich wharf May 18, 2020, 5:23 AM

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Python is literally psuedocode

unkempt rock May 18, 2020, 5:23 AM

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fr

ionic void May 18, 2020, 5:25 AM

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Does Java have an equivalent to Python dunder?

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Or is this purely a unique Python feature?

rich wharf May 18, 2020, 5:26 AM

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Maybe constructors

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But I'm not sure much else

ionic void May 18, 2020, 5:26 AM

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Hm possibly, I tried to compare those two as well.

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But dunder doesn't even create an object.

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It's just ...there.

wide shuttle May 18, 2020, 5:28 AM

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That dunder is a name assigned to some object in memory

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The biggest concentration of dunders you'll find in the Python datamodel

rich wharf May 18, 2020, 5:28 AM

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Oh, I thought you were talking about dunder/magic methods

ionic void May 18, 2020, 5:29 AM

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They aren't the same?

wide shuttle May 18, 2020, 5:29 AM

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They're the hooks you can use to make your classes behave as built-in Python objects and to hook into various parts in an object's lifetime

unkempt rock May 18, 2020, 5:29 AM

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ye

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wait

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does java not have it

ionic void May 18, 2020, 5:29 AM

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Not that I know of.

raven ridge May 18, 2020, 5:29 AM

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Most of the dunder methods are essentially for operator overloading, which Java doesn't generally support.

unkempt rock May 18, 2020, 5:29 AM

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i dont think so

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i think just python

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how tho

ionic void May 18, 2020, 5:30 AM

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When I learn Python I try to match everything to java haha

unkempt rock May 18, 2020, 5:30 AM

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like isnt java supposed to have more capabilities than python

ionic void May 18, 2020, 5:30 AM

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No.

unkempt rock May 18, 2020, 5:30 AM

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o

ionic void May 18, 2020, 5:30 AM

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They have different strengths.

raven ridge May 18, 2020, 5:31 AM

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C++ has pretty close analogues to some Python dunders, with things like operator+ and operator<<

ionic void May 18, 2020, 5:31 AM

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The biggest difference is probably that Java is statically typed.

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So it's faster.

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hm oh

unkempt rock May 18, 2020, 5:32 AM

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is it really necessary tho

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to have dunder

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like

ionic void May 18, 2020, 5:32 AM

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I guess.

unkempt rock May 18, 2020, 5:32 AM

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what makes it different from dictionary

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except that its hundred times more organized

ionic void May 18, 2020, 5:32 AM

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But the tutorial that I did talked about it, and I was confused.

primal girder May 18, 2020, 5:32 AM

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If you're looking for speed, then c++ is what you're after

unkempt rock May 18, 2020, 5:32 AM

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yes c++ does all the stuff

primal girder May 18, 2020, 5:32 AM

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Java isn't particularly useful

raven ridge May 18, 2020, 5:33 AM

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Java isn't just faster because of static typing (though that does make it do less work). The fact that it compiles to bytecode with a JIT is its biggest performance advantage over Python.

unkempt rock May 18, 2020, 5:33 AM

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did my PhD in quantum computing where nothing but speed is important

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actually almost all the stuff was written in C or Fortran

ionic void May 18, 2020, 5:33 AM

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Yes that's true.

unkempt rock May 18, 2020, 5:34 AM

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but you can always go a step further and write assembler

ionic void May 18, 2020, 5:34 AM

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But then Python is more human readable than those languages.

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That's also a strength.

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It's easier to learn.

primal girder May 18, 2020, 5:34 AM

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Python and c++ work quite well together

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Libraries like pybind11 are awesome

raven ridge May 18, 2020, 5:36 AM

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Dunder isn't necessary. Python chooses to pass self explicitly, unlike Java passing this implicitly. So, one could imagine an alternative to dunders where instead of specially named methods, you call a method anything you want, and then call a function or use a decorator to register it to the object model.

primal girder May 18, 2020, 5:36 AM

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You can do the performance critical stuff in c++ and expose that to python easily

unkempt rock May 18, 2020, 5:36 AM

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or just use Numpy instead of basic python

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and you get very close

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without having to write any C++

raven ridge May 18, 2020, 5:37 AM

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That is, you can see dunders as a way to do something implicitly (with magic methods with known names) that could instead be done explicitly (with explicit registration to make non-magic methods magic)

ionic void May 18, 2020, 5:38 AM

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ah ok, but do you create the "known names" or are they premade?

unkempt rock May 18, 2020, 5:39 AM

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there's something i never tried doing before

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how do i list all the words from a file

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like

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slap it into a list

raven ridge May 18, 2020, 5:40 AM

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With Python's data model the known names are things like __init__ and __add__ - the interpreter knows them and looks for them.

ionic void May 18, 2020, 5:40 AM

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Use a for loop? and append each word into the list from your file?

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I've done it with an URL before, I haven't gotten to Python I/O yet.

uncut sage May 18, 2020, 5:41 AM

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read each line
split each line into words
add each word to a set so there are no duplicates

ionic void May 18, 2020, 5:41 AM

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Oh that's good

uncut sage May 18, 2020, 5:41 AM

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@unkempt rock

unkempt rock May 18, 2020, 5:42 AM

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uh

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how do i determine line

uncut sage May 18, 2020, 5:43 AM

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When you read from a text file Python automatically reads a line at a time unless you specify otherwise

ionic void May 18, 2020, 5:43 AM

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^ you just need to open the file and put it in read mode

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well the default is read.

unkempt rock May 18, 2020, 5:45 AM

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Well, there are countless tutorials on how to read a file in python

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just look into one of those

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oh wait nvm

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im actually braindead

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smhmyhead

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didnt even need to split into a list lmao

wide shuttle May 18, 2020, 5:55 AM

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With Python's data model the known names are things like __init__ and __add__ - the interpreter knows them and looks for them.
@raven ridge

I really like this way of doing it, as it means that I know what to look for as well. It should also set apart the functions/names that have a special meaning in the data model.

raven ridge May 18, 2020, 5:56 AM

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Oh, I agree that it's more elegant than the alternatives - I was just saying that there definitely are alternatives that could have worked.

wide shuttle May 18, 2020, 5:58 AM

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Yeah, I wasn't trying to argue that point, more trying to add that I like the decision that was made

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but, there are alternatives

raven ridge May 18, 2020, 5:59 AM

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It's also better than C++'s approach - that also has magic names, but a) some of those magic functions can be defined outside the class, which is madness when it comes to tracking down how things will behave, and b) they choose operator$OP as the function name, which is ambiguous for things like pre- vs post- increment and requires a whole ugly hack to fix

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If I recall correctly, some operator overloads must be defined as free functions in C++, in fact...

wide shuttle May 18, 2020, 6:03 AM

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I was just looking at it; I haven't touched C++ in a long time

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The current page I'm looking at has it the other way around, that some overloadings cannot be a non-member

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But, it's been too long and I've never really went far into C++ (https://en.cppreference.com/w/cpp/language/operators)

raven ridge May 18, 2020, 6:06 AM

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Stream extraction and insertion

The overloads of operator>> and operator<< that take a std::istream& or std::ostream& as the left hand argument are known as insertion and extraction operators. Since they take the user-defined type as the right argument (b in a@b), they must be implemented as non-members.

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I was double checking myself on that same page 😀

wide shuttle May 18, 2020, 6:10 AM

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Ah, nice. I should have read more

raven ridge May 18, 2020, 6:11 AM

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It's kinda the same problem as Python solves with the reflected dunders, come to think of it

undone hare May 18, 2020, 6:46 AM

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3.9 has some cool features so far

fossil pumice May 18, 2020, 8:13 AM

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@undone hare what are you favorite ones?

undone hare May 18, 2020, 8:14 AM

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Probably the builtin generic types https://docs.python.org/3.9/whatsnew/3.9.html#pep-585-builtin-generic-types

fossil pumice May 18, 2020, 8:15 AM

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hell yeah, that's a nice change

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such a tiny change but very appreciated

undone hare May 18, 2020, 8:15 AM

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Yup

wide shuttle May 18, 2020, 8:16 AM

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I'm excited about PEG and what it will hold for the future

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It's the new parser

undone hare May 18, 2020, 8:16 AM

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Yup, that's quite interesting too

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The PR for generic types is also quite interesting https://github.com/python/cpython/pull/18239

GitHub

bpo-39481: Implementation for PEP 585 by gvanrossum · Pull Request ...

I consider this a finished prototype now. We've got everything working, and then some (e.g. pickle), and while we found a fair number of minor issues with PEP 585, the main conclusion is th...

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The new parser also has a wonderful +27,058 additions, −147 deletions haha

deft pagoda May 18, 2020, 9:28 AM

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new parser is a PEG?

undone hare May 18, 2020, 9:38 AM

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Yup

deft pagoda May 18, 2020, 9:40 AM

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nice, i wanted to implement my own toy peg a few months ago, but moved past it

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Dictionary Merge & Update Operators¶
Merge (|) and update (|=) operators have been added to the built-in dict class. See PEP 584 for a full description. (Contributed by Brandt Bucher in bpo-36144.)

wide shuttle May 18, 2020, 9:56 AM

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That is pretty cool

deft pagoda May 18, 2020, 10:04 AM

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i'm gonna guess this is what i'll be using the most

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would be cool if it added things to a ChainMap too

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maybe ChainMap already has it, i've never looked

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it doesn't 😦

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oh i actually wanted this not that long ago:

PEP 616: New removeprefix() and removesuffix() string methods¶
str.removeprefix(prefix) and str.removesuffix(suffix) have been added to easily remove an unneeded prefix or a suffix from a string. Corresponding bytes, bytearray, and collections.UserString methods have also been added. See PEP 616 for a full description. (Contributed by Dennis Sweeney in bpo-18939.)

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now i have to find out where it was

ruby spruce May 18, 2020, 10:38 AM

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Is next Python 3.10 or 4?

gray mirage May 18, 2020, 10:38 AM

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3.10

ruby spruce May 18, 2020, 10:44 AM

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😭

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I hope we get Py4 in one day

unkempt rock May 18, 2020, 10:59 AM

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true

jovial pagoda May 18, 2020, 10:59 AM

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I have 64-bit processor, so it is better to have 64-bit python or 32-bit python?

undone hare May 18, 2020, 11:00 AM

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Dictionary Merge & Update Operators¶
Merge (|) and update (|=) operators have been added to the built-in dict class. See PEP 584 for a full description. (Contributed by Brandt Bucher in bpo-36144.)

@deft pagoda well, you could already do {**dict1, **dict2}, but not a lot of people know about it apparently, according to the PEP

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@jovial pagoda 64bits for sure

jovial pagoda May 18, 2020, 11:01 AM

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but, it will work same, right?

deft pagoda May 18, 2020, 11:01 AM

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that just doesn't look pretty

wide shuttle May 18, 2020, 11:02 AM

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The PEP says this:

{**d1, **d2}

Dict unpacking looks ugly and is not easily discoverable. Few people would be able to guess what it means the first time they see it, or think of it as the "obvious way" to merge two dicts.

undone hare May 18, 2020, 11:02 AM

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@jovial pagoda yup, but the 64bits is faster and can use more than 4Gb of memory

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I don't think it looks that ugly, but that's isn't the most obvious thing ever yeah

deft pagoda May 18, 2020, 11:03 AM

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ha, agree with PEP

undone hare May 18, 2020, 11:04 AM

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Unpacking inside constructors works for lists and sets too, and has its use cases

oblique crystal May 18, 2020, 11:05 AM

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that just doesn't look pretty
or how to say "looks ugly" not using word "ugly"

deft pagoda May 18, 2020, 11:05 AM

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i'm a glass twice as big as it needs to be kind of guy

oblique crystal May 18, 2020, 11:06 AM

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having those dict operators is cool really, should make codes quite nicer

raven pike May 18, 2020, 11:07 AM

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I never get zipping and unpacking man. I just don't get it. I don't remember c++ had this one, that's the only languages I am familiar with except python

peak spoke May 18, 2020, 11:08 AM

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I think without knowing it beforehand, the unpacking is a bit clearer than update imo

raven pike May 18, 2020, 11:10 AM

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Guys can't we decleare a variable without assigning anything to it? Just decleare an address for example

flat gazelle May 18, 2020, 11:10 AM

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not really

dreamy tartan May 18, 2020, 11:10 AM

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Why would you need to do that in python?

flat gazelle May 18, 2020, 11:10 AM

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there is no reason to

undone hare May 18, 2020, 11:11 AM

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Nope you can't, and there's no so much point in doing so, because of Python's nature

dreamy tartan May 18, 2020, 11:11 AM

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That's more of a C thing to do, because you have to keep variables a certain type.

You do not have to do this in python.

flat gazelle May 18, 2020, 11:11 AM

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only functions have their own scope, and in those you can use global to make a variable global even if there is no outer variable

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if a:
    b = 7
else:
    b = 6
print(b)
```this works

deft pagoda May 18, 2020, 11:13 AM

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you can do it in classes

raven pike May 18, 2020, 11:13 AM

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you can do it in classes
@deft pagoda like how?

flat gazelle May 18, 2020, 11:14 AM

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just

class U:
    name
``` afaik

deft pagoda May 18, 2020, 11:14 AM

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by __prepare__ passing a default dict

flat gazelle May 18, 2020, 11:14 AM

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optionally with a type hint

raven pike May 18, 2020, 11:15 AM

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Oh, this sounds interesting. İs I'll dig into that

deft pagoda May 18, 2020, 11:15 AM

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!e

from itertools import count

class IncrDict(dict):
    def __init__(self, start=0, step=1):
        self.counter = count(start, step)

    def __missing__(self, key):
        if key.startswith('__'):
            raise KeyError(key)

        self[key] = next(self.counter)
        return self[key]

class EnumMetaclass(type):
    def __prepare__(*args, **kwargs):
        start = kwargs.get('start', 0)
        step = kwargs.get('step', 1)
        return IncrDict(start, step)

class Enum(metaclass=EnumMetaclass):
    def __init_subclass__(cls, **kwargs):
        """Pull kwargs from class def"""

class Fruit(Enum, start=10, step=15):
    APPLE
    BANANA
    KIWI

print(Fruit.APPLE, Fruit.BANANA, Fruit.KIWI)

fallen slateBOT May 18, 2020, 11:15 AM

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@deft pagoda :white_check_mark: Your eval job has completed with return code 0.

10 25 40

deft pagoda May 18, 2020, 11:16 AM

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APPLE, BANANA, and KIWI weren't defined!

raven pike May 18, 2020, 11:17 AM

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Interesting. Thanks for sharing

peak spoke May 18, 2020, 11:18 AM

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Not really something I'd want to see in real code

deft pagoda May 18, 2020, 11:18 AM

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this is real code

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this is the best Enum class i've ever seen

undone hare May 18, 2020, 11:19 AM

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All of that just because salt is too lazy to type 6 digits

deft pagoda May 18, 2020, 11:19 AM

#

pff, i've done worse things

flat gazelle May 18, 2020, 11:19 AM

#

I mean, how often do you really care about what exactly the ordinals in an enum are. You just need them distinct, and sometimes on distinct bits too

deft pagoda May 18, 2020, 11:20 AM

#

i hacked kivy's widget.py to ChainMap kivy Properties in the Widget class defs

#

for convenience

raven pike May 18, 2020, 11:20 AM

#

One of you said 64 bit version of python could eat much more ram, so if I replace mine with 32 bit, the ram usage would decreased? I'm having trouble working in vscode, and out of my 8 GB ram using chrome for problem solving etc I left with only 400 mb so many times. Although I'm using vs code's interactive python screen as well

flat gazelle May 18, 2020, 11:21 AM

#

not really, it is more that the 32bit will not drain all your ram if you overallocate

undone hare May 18, 2020, 11:22 AM

#

Well, python will use the same amount of bits to represent a value, even if you use a 32bits version or a 64bits

visual shadow May 18, 2020, 11:22 AM

#

dont use 32bit python, the headaches associated are a lot greater

raven pike May 18, 2020, 11:22 AM

#

Oh ok. Just thought do that and boom. Free ram 😄

visual shadow May 18, 2020, 11:22 AM

#

haha. if you need more ram, just download more ram online! (ps, that was a joke!)

flat gazelle May 18, 2020, 11:23 AM

#

https://downloadmoreram.com/

visual shadow May 18, 2020, 11:23 AM

#

i knew it was coming too haha!

undone hare May 18, 2020, 11:23 AM

#

I was going to do that >.>

visual shadow May 18, 2020, 11:24 AM

#

But yeah, stick with 64bit python, and dont worry about looking at the ram your system is using. your system tries it best to allocate and deallocate memory as necessary

#

if you dont have a lot of applications open at the same time, you should be fine for normal use. if you load something that's too big to fit in memory, then the "application" isnt the problem, the volume of data is.

flat gazelle May 18, 2020, 11:24 AM

#

I have pushed chrome with ~100 tabs to 200MB of RAM

peak spoke May 18, 2020, 11:24 AM

#

@deft pagoda well in general people should stay away from metaclasses imo, or use the builtin simple ones like Enum which don't do that much black magic

visual shadow May 18, 2020, 11:24 AM

#

in that case, you use other techniques to work with the data

undone hare May 18, 2020, 11:25 AM

#

The 32 bits version might even have more overhead than the 64bits

flat gazelle May 18, 2020, 11:25 AM

#

the OS is pretty good at managing memory

peak spoke May 18, 2020, 11:25 AM

#

Explicit is better than implicit and all

deft pagoda May 18, 2020, 11:25 AM

#

i think in general people should use meta classes more often to produce more interesting libraries with simpler interfaces

visual shadow May 18, 2020, 11:25 AM

#

iirc the 32bit python has a hardcap on using only 2gb ram for python. it's a horrid environment to work in, very starved for resources

flat gazelle May 18, 2020, 11:25 AM

#

sometimes, that is nice

#

when doing which, if you screw up, would use a lot ram

#

can be hard to shut it down in time

undone hare May 18, 2020, 11:25 AM

#

Meta classes are here to provide more DSL, and that's something I think we should have more in python

peak spoke May 18, 2020, 11:26 AM

#

metaclasses usually lead to dynamic code which just gets more confusing for tools and people

visual shadow May 18, 2020, 11:27 AM

#

what's dsl?

peak spoke May 18, 2020, 11:27 AM

#

if I saw

class Fruit(Enum, start=10, step=15):
    APPLE
    BANANA
    KIWI

as a random snippet in a lib I'd have to guess what it does

flat gazelle May 18, 2020, 11:27 AM

#

personally, I prefer DSLs in separate files, rather than strapped onto existing syntax

#

like kvlang

#

Domain Specific Language

undone hare May 18, 2020, 11:27 AM

#

^

visual shadow May 18, 2020, 11:28 AM

#

i see. that phrase doesnt mean much to me atm, so i'd have to look into it

flat gazelle May 18, 2020, 11:28 AM

#

well, there are some languages where DSLs are convenient, like FORTH, LISP, kotlin and such

#

but in python, it does not work all that well imo

deft pagoda May 18, 2020, 11:29 AM

#

i'm not such a stickler for conformity -- if you can make a simple to use interface with a metaclass, i think you should do it -- it's not like you can't document what you're doing

molten onyx May 18, 2020, 11:29 AM

#

I don't like this "hack" but I do think that enum.auto should definitely be a descriptor

deft pagoda May 18, 2020, 11:30 AM

#

pythons enums look awful

wide shuttle May 18, 2020, 11:36 AM

#

I think there's a lot of value in having things behave in a predictable way

deft pagoda May 18, 2020, 11:44 AM

#

i bet that Enum class behaves the same way every time, thats predictable!

wide shuttle May 18, 2020, 11:49 AM

#

Very. But you know what I mean.

deft pagoda May 18, 2020, 11:53 AM

#

the sly parser uses the magic @_ decorator in class defs

wide shuttle May 18, 2020, 1:58 PM

#

@wide moss This channel is specifically meant to discuss the Python programming language itself, from a higher perspective. You could try one of our off-topic channels, but we're a Python-specific server. This is a C/C++ Discord server: https://discord.gg/vnyVmAE.

sacred tinsel May 18, 2020, 2:03 PM

#

is there a style guide for method definition order, i.e. dunder property static abstract.. ?

#

looks like PEP8 doesn't mention that

#

also, in the case of an abstract property, I'm not sure whether to group it with properties or abstract methods

grave jolt May 18, 2020, 2:06 PM

#

I think it's reasonable to define __init__, __repl__ and __str__ on top

sacred tinsel May 18, 2020, 2:07 PM

#

yeah, I do dunders at the top, but for the rest, I'm not sure

#

I think in Java the convention is to do static at the very top

#

I don't do staticmethods much - if it's a non-bound helper accessed from within only I put it as a module-level func

wide shuttle May 18, 2020, 2:08 PM

#

That's what I recently started doing more and more as well

sacred tinsel May 18, 2020, 2:08 PM

#

it's so nice

grave jolt May 18, 2020, 2:08 PM

#

there's this answer on SO
https://stackoverflow.com/questions/10289461/what-is-a-good-way-to-order-methods-in-a-python-class/36967648
but that's just someone's opinion

peak spoke May 18, 2020, 2:09 PM

#

I usually lean towards putting not that functional things like str towards the end, along with classmethod constructors and function helpers

sacred tinsel May 18, 2020, 2:10 PM

#

it's interesting because I remember chatting to the professor who led my bsc dissertation about this (in relation to C++), he said it should tell a story and the interface should be at the bottom, not the top

peak spoke May 18, 2020, 2:10 PM

#

the others mostly grouped by functionality between that (and of course init on top if there is one)

grave jolt May 18, 2020, 2:10 PM

#

I think consistency is more important than a particular choice here. If a class has 100 methods, maybe there's something wrong with it

peak spoke May 18, 2020, 2:11 PM

#

the main constructor/initialization method should be at the top imo but beyond that it's preference

grave jolt May 18, 2020, 2:11 PM

#

True

sacred tinsel May 18, 2020, 2:11 PM

#

I think the reasoning there was that if you read the class top to bottom, you shouldn't come across references to things that you haven't seen defined yet

#

but overall I believe the opposite is preferred by many

#

i.e. interface at the top

#

which makes sense too

wide shuttle May 18, 2020, 2:13 PM

#

I struggle with the question as well

#

I'm not always sure what the best option is

#

Too bad there's no black for method definition order

sacred tinsel May 18, 2020, 2:15 PM

#

with this abstract property, I'm tempted to put it above the __init__

#

ahh, it's so difficult

#

I wish there was a way to have an abstract attribute

grave jolt May 18, 2020, 2:17 PM

#

Maybe someone could make a metaclass for that🧂

wide shuttle May 18, 2020, 2:19 PM

#

With a bit of magic, you could do head surgery on the child class (as Beazley calls it) and make it raise an error when you try to intantiate it if it does not define certain attributes at class definition time

#

It's just "custom", so you may upset people

sacred tinsel May 18, 2020, 2:19 PM

#

yeah, I don't like that

#

I'm aware that it's possible, what I mean is "I wish abc supported it"

molten onyx May 18, 2020, 2:19 PM

#

There's no real way to know what attributes a child defines as __init__ is only called after the instance exists

grave jolt May 18, 2020, 2:20 PM

#

Only if it's required to be a property for some weird reason.

#

Maybe you can redefine __init__ on instance creation. That will show the contract breaching in a test case.

sacred tinsel May 18, 2020, 2:23 PM

#

I wouldn't mind enforcing it via tests, but that's pretty difficult, too

#

the ABC will give you its subclasses, but only if their definitions had run at that point

grave jolt May 18, 2020, 2:24 PM

#

Maybe you can look for both properties and annotations.

#

But that would create some ugly redundant annotations.

#

class Point:
    x: float
    y: float
    def __init__(self, x: float, y: float):
        """Constructor takes two floating-point numbers and creates a 2D point"""
        if not isinstance(x, float):
            print(f"Invalid argument: {x=}")
        if not isinstance(y, float):
            print(f"Invalid argument: {y=}")
        self.x, self.y = x, y

wide shuttle May 18, 2020, 2:26 PM

#

I honestly thought you meant a class attribute

#

Not an instance attribute

sacred tinsel May 18, 2020, 2:26 PM

#

I meant class attrs

grave jolt May 18, 2020, 2:26 PM

#

oh

#

Then you can detect them on class defintion, right?

sacred tinsel May 18, 2020, 2:29 PM

#

yeah, but it's still "custom"

#

I wouldn't consider that out of the box functionality

grave jolt May 18, 2020, 2:29 PM

#

true

#

But maybe it will be obvious if you call it my_property: AbstractProperty

#

or something like that

#

Can't you just say my_property = abc.abstractproperty()?

#

Oh, it won't be enforced.

sacred tinsel May 18, 2020, 2:34 PM

#

ideally, I'd want this:

class MyABC(ABC):
  attr: some_type  # Somehow express that this must be provided by the child

class Implementation(MyABC):
  ...  # This fails on class creation because attr isn't defined

#

afaik, the only way this is supported by abc is having a property decorated as abc.abstractmethod

grave jolt May 18, 2020, 2:44 PM

#

!e

from abc import abstractproperty

class AbstractPropertyEnforcer(type):
    def __new__(cls, name, bases, newattrs):
        if len(bases) > 0:
            base = bases[0]
            for prop_name, prop_value in base.__dict__.items():
                if (
                    isinstance(prop_value, abstractproperty)
                    and prop_name not in newattrs
                ):
                    raise TypeError(
                        f"Child class {name} must implement the abstract "\
                        f"property '{prop_name}'."
                    )
        return super().__new__(cls, name, bases, newattrs)

class Base(metaclass=AbstractPropertyEnforcer):
    x = abstractproperty()

class Child1(Base):
    x = 42

class Child2(Base):
    y = 42

fallen slateBOT May 18, 2020, 2:44 PM

#

@grave jolt :x: Your eval job has completed with return code 1.

001 | Traceback (most recent call last):
002 |   File "<string>", line 24, in <module>
003 |   File "<string>", line 12, in __new__
004 | TypeError: Child class Child2 must implement the abstract property 'x'.

wide shuttle May 18, 2020, 2:44 PM

#

You could also do this with __init_subclass__

grave jolt May 18, 2020, 2:45 PM

#

oh

#

True, that's much better

lost nexus May 18, 2020, 2:45 PM

#

Is there any advantage to defining a sequence with its respective literal rather than calling it? For example [] over list()

grave jolt May 18, 2020, 2:46 PM

#

well

wide moss May 18, 2020, 2:46 PM

#

what is a great randamizer function

grave jolt May 18, 2020, 2:47 PM

#

maybe dict() might give some advantage over {} if you're working with sets a lot in a module

lost nexus May 18, 2020, 2:47 PM

#

So, is it a visual preference or does it play any role in how efficient the code is?

grave jolt May 18, 2020, 2:48 PM

#

probably ```py
In [25]: %timeit x = []
25.5 ns ± 0.142 ns per loop (mean ± std. dev. of 7 runs, 10000000 loops each)

In [26]: %timeit x = list()
68.7 ns ± 0.683 ns per loop (mean ± std. dev. of 7 runs, 10000000 loops each)

wide shuttle May 18, 2020, 2:48 PM

#

It does make a difference, yeah

lost nexus May 18, 2020, 2:48 PM

#

I see

wide shuttle May 18, 2020, 2:48 PM

#

For the list() variant, you load a name and call a function

undone hare May 18, 2020, 2:49 PM

#

Yup, list() is a function

grave jolt May 18, 2020, 2:49 PM

#

!e

__import__("dis").dis(lambda: list())
print()
__import__("dis").dis(lambda: [])

fallen slateBOT May 18, 2020, 2:49 PM

#

@grave jolt :white_check_mark: Your eval job has completed with return code 0.

001 |   1           0 LOAD_GLOBAL              0 (list)
002 |               2 CALL_FUNCTION            0
003 |               4 RETURN_VALUE
004 | 
005 |   3           0 BUILD_LIST               0
006 |               2 RETURN_VALUE

undone hare May 18, 2020, 2:49 PM

#

As [] is directly BUILD_LIST

grave jolt May 18, 2020, 2:50 PM

#

well, technically it's a class, but it's still some object you have to call.

#

And BUILD_LIST just allocates some memory and copies some stuff into there.

undone hare May 18, 2020, 2:50 PM

#

Well, that's a bound function :>

grave jolt May 18, 2020, 2:50 PM

#

(probably)

wide shuttle May 18, 2020, 2:51 PM

#

I call it a function because it's listed in the documentation as a built-in function

#

I'm not actually sure how it's implemented.

grave jolt May 18, 2020, 2:51 PM

#

It's kinda self-contradicting 🤔

📎 unknown.png

wide shuttle May 18, 2020, 2:51 PM

#

I've not checked

#

haha

#

that's interesting

grave jolt May 18, 2020, 2:52 PM

#

Maybe they did that so that beginners aren't confused too much while reading the docs.

undone hare May 18, 2020, 2:52 PM

#

Well, that's the python docs haha

wide shuttle May 18, 2020, 2:52 PM

#

I think the Python docs are excellent for language docs

undone hare May 18, 2020, 2:52 PM

#

or just two different people wrote it

wide shuttle May 18, 2020, 2:52 PM

#

They're not perfect, sure

undone hare May 18, 2020, 2:52 PM

#

They are really good yeah

#

But that's funny to see all the issues about docs on bpo

lost nexus May 18, 2020, 2:53 PM

#

I learned 75% of what I know of Python off the offline docs I randomly found on my drive

sacred tinsel May 18, 2020, 2:53 PM

#

I hate that the docs never show up at the top of my google searches

#

it's always some magicalpythonsnakegrandmasters.org tutorial

wide shuttle May 18, 2020, 2:53 PM

#

I've added a custom shortcut to my firefox for that

sacred tinsel May 18, 2020, 2:53 PM

#

and when I actually find the doc link, it's 2.7

wide shuttle May 18, 2020, 2:53 PM

#

p3doc <search term>

undone hare May 18, 2020, 2:54 PM

#

Tbh I don't google anymore, I !d-ing

zenith topaz May 18, 2020, 2:54 PM

#

Python 2 is often the first one.
Python 3 the seond for me

wide shuttle May 18, 2020, 2:54 PM

#

and p3doc searches the docs specifically

undone hare May 18, 2020, 2:54 PM

#

Well, there is a big red warning now on the py2 docs

#

Docstrings are also useful

wide shuttle May 18, 2020, 2:55 PM

#

📎 2020-05-18_16-54.png

#

📎 2020-05-18_16-54_1.png

#

That's what I did

undone hare May 18, 2020, 2:55 PM

#

That's pretty cool

wide shuttle May 18, 2020, 2:55 PM

#

It's just a firefox feature

wide moss May 18, 2020, 2:55 PM

#

how do you make text bubble to show code ?

wide shuttle May 18, 2020, 2:56 PM

#

Try the !codeblock tag in #bot-commands

peak spoke May 18, 2020, 2:56 PM

#

making google search the good docs without writing out the url at the start can sometimes be a tad hard

#

for some things I tend to get docs from 15 years ago

undone hare May 18, 2020, 2:57 PM

#

It looks like BUILD_STRING is a wrapper around the PyObject* STRINGLIB_NEW(STRINGLIB_CHAR*, Py_ssize_t) function, I'm looking for the list

wide shuttle May 18, 2020, 2:57 PM

#

Python 2 docs have really good SEO and I don't think it helps that you can change the version in the bar at the top

#

If you do that, Google assumes you've found what you're looking for with that Py2 docs link

peak spoke May 18, 2020, 2:57 PM

#

at least they're better than the ones which pop up first but are missing the selector (or completely different structure)

grave jolt May 18, 2020, 3:00 PM

#

back to the drawing board...

📎 unknown.png

#

Or maybe that's just a mypy bug?

undone hare May 18, 2020, 3:04 PM

#

Here is BUILD_LIST https://github.com/python/cpython/blob/master/Python/ceval.c#L2779, it looks like list goes through PyList_New() anyway, I guess it is faster beacuse list() has the overhead of calling a function

GitHub

python/cpython

The Python programming language. Contribute to python/cpython development by creating an account on GitHub.

grave jolt May 18, 2020, 3:05 PM

#

and loading a global name

undone hare May 18, 2020, 3:05 PM

#

Yup

#

Would someone here already set up PyCharm to dev CPython directly? I'm having a really hard time to make it find modules and such, and I can't find anything online

true ridge May 18, 2020, 3:31 PM

#

I dont know if pycharm supports it but for finding functions definitions etc, we have a build target that outputs tags file (make tags)

#

I'm using it with geany (and geany-c-tags, https://plugins.geany.org/geanyctags.html)

undone hare May 18, 2020, 3:41 PM

#

Oh hey, I remember seeing your name on bpo haha

deft pagoda May 18, 2020, 3:42 PM

#

i actually implemented that thing for someone in a help channel --- the init_subclass enforcing attributes of the children

undone hare May 18, 2020, 3:43 PM

#

I'll try geany thanks!

deft pagoda May 18, 2020, 3:45 PM

#

need a ipython line magic for opening pydocs

#

# -----------------------------------------
# ---------- Quick Pydocs %docs -----------
# -----------------------------------------

import webbrowser

@register_line_magic
def docs(line):
    webbrowser.open(f'https://docs.python.org/3/search.html?q={line}')

del docs

peak spoke May 18, 2020, 3:56 PM

#

Could download the inventory and search like !d does

undone hare May 18, 2020, 4:20 PM

#

The first beta of Py3.9 should be out today apparently

peak spoke May 18, 2020, 4:22 PM

#

the pep for the new release cycle has a nice chart for the periods

#

!pep 602

fallen slateBOT May 18, 2020, 4:22 PM

#

**PEP 602 - Annual Release Cycle for Python**

Link

Status

Accepted

Python-Version

3.9

Created

04-Jun-2019

Type

Informational

true ridge May 18, 2020, 4:37 PM

#

Oh hey, I remember seeing your name on bpo haha
@undone hare haha, nice. I just learnt that discord can automatically match ascii characters with different styles (such as s in my surname), so I switched back to my original name.

grizzled vigil May 19, 2020, 3:29 AM

#

@wide shuttle

I call it a function because it's listed in the documentation as a built-in function
Simply calling list() a function is accurate enough for 99% of use cases, at least IMO. I suspect that's why it's grouped as a built-in function, even if it may technically not be.

@grave jolt

Maybe they did that so that beginners aren't confused too much while reading the docs.
Most of the Python docs tend to lean in the direction of focusing on being "practically accurate" rather than being 100% semantically accurate. I'd consider it to be a case of practicality > purity.

undone hare May 19, 2020, 7:04 AM

#

One thing that I'd like to see on the docs is a link to the source code though, to check the implementation quickly, but the docs have a pretty good balance between correctness and readability imo

deft pagoda May 19, 2020, 7:58 AM

#

docs have a link to source

undone hare May 19, 2020, 8:01 AM

#

Yes there's a per module link, but not a per element link to the right line, and some doesn't even have a link, like the built in

prime estuary May 19, 2020, 8:40 AM

#

One difficulty is that that would need to be somehow dynamic so it updates every time someone commits to the file.

true ridge May 19, 2020, 11:31 AM

#

https://pythoninsider.blogspot.com/2020/05/python-390b1-is-now-available-for.html

wide shuttle May 19, 2020, 11:37 AM

#

Yeah, cool, I was just reading that

molten onyx May 19, 2020, 11:38 AM

#

Does this mean 3.9 is on feature freeze

#

oh hey

#

https://bugs.python.org/issue1635741

#

This seems to be the same memory leak I never reported yert

true ridge May 19, 2020, 11:54 AM

#

Does this mean 3.9 is on feature freeze
@molten onyx yep, no new features to 3.9 (unless RM decides otherwise)

undone hare May 19, 2020, 12:04 PM

#

It looks like all major 3.9 features have already been merged anyway

#

Are you hyped about the new parser @true ridge ? lemon_pika

true ridge May 19, 2020, 12:05 PM

#

Very much

#

The only thing I'm sad about is deprecation of lib2to3 :(

#

That was a must, since the parser generator inside of it was LL(1) and in the future won't be able to parse new python code, though it was nice to have a CST implementation on the stdlib

undone hare May 19, 2020, 12:07 PM

#

Oh, that’s a bit sad that they deprecated 2to3

#

The new parser looks pretty cool

#

Oh well, hello news

#

I’m really wondering why posting the download link twice though, it seems like that’s the case for every annoucement, that’s pretty weird

boreal umbra May 19, 2020, 3:28 PM

#

does datetime.timedelta not support formatting their duration as a string in a custom format?

shy vine May 19, 2020, 3:30 PM

#

Nope

boreal umbra May 19, 2020, 3:34 PM

#

This is very upsetting for me.

#

I might have to look into what it would take to implement that.

tame bay May 19, 2020, 3:36 PM

#

Yo, is there anyway I can remove blank lines while reading my text?

peak spoke May 19, 2020, 3:36 PM

#

ought to have a lib, but the format it does is pretty neat imo; not sure if weeks could be included without getting into time weirdness

sturdy timber May 19, 2020, 3:37 PM

#

@tame bay See #❓｜how-to-get-help , this isn't the channel for that sort of question

tame bay May 19, 2020, 3:38 PM

#

Haha, my bad, it's just I'm in a hurry, and the channel is closed

#

So, what do you guys usually talk about in here?

north root May 19, 2020, 3:38 PM

#

it's in the channel topic

Discussion on the use cases, implementation and future of the Python programming language including PEPs, new releases, the standard library and the overall design of the language.

tame bay May 19, 2020, 3:39 PM

#

Oh, interesting!

vale bolt May 19, 2020, 4:29 PM

#

can anyone explain why python cant be used on client side the same way javascript is?

flat gazelle May 19, 2020, 4:29 PM

#

because browsers run javascript. Anything that wants to run client side has to be javascript

unkempt rock May 19, 2020, 4:29 PM

#

the browser can't run it

flat gazelle May 19, 2020, 4:30 PM

#

everything else just compiles to javascript. (well there is also WASM)

#

python actually does have a runtime for JS (brython), but it is not really production ready

vale bolt May 19, 2020, 4:30 PM

#

Oh ok, then why dont browsers allow more languages?

flat gazelle May 19, 2020, 4:30 PM

#

because all of them would have to agree on one

#

and implement it

#

according to a very strict standard

lost nexus May 19, 2020, 4:31 PM

#

Why does Python allocate so much memory to dictionaries?

flat gazelle May 19, 2020, 4:31 PM

#

they are hashtables, and they need quite a bit of space because of that

#

and also, it overallocates in case the dict grows

vale bolt May 19, 2020, 4:32 PM

#

ok thanks man

lost nexus May 19, 2020, 4:32 PM

#

Don't all sequences over-allocate to pre-allocate?

gray mirage May 19, 2020, 4:32 PM

#

tuples and other fixed-size ones don't

flat gazelle May 19, 2020, 4:32 PM

#

ye, frozenset does not either.

#

neither do strings

lost nexus May 19, 2020, 4:32 PM

#

I see

gray mirage May 19, 2020, 4:32 PM

#

yeah, they're immutable so there's no point

inner edge May 19, 2020, 4:58 PM

#

What's more efficient, .endswith("baz") or string[-n:]?

deft pagoda May 19, 2020, 5:01 PM

#

use the more explicit one and don't worry about anything else

peak spoke May 19, 2020, 5:07 PM

#

readability first, speed last or when it becomes a bottleneck

boreal umbra May 19, 2020, 5:21 PM

#

I think it would be pretty simple to implement custom duration formatting with datetime.timedelta in a datetime.datetime.strftime like way using regular expressions. Do you think that would get immediately shot down?

peak spoke May 19, 2020, 5:27 PM

#

I don't think there's as much utility for it with deltas compared to datetimes, and those just call the C function

boreal umbra May 19, 2020, 5:27 PM

#

deltas?

#

oh, timedeltas. I thought maybe "delta" was a separate thing.

#

But I was just looking at the implementation for strftime and it looks like it's written in Python

peak spoke May 19, 2020, 5:29 PM

#

Like, I don't want to represent a difference in units that are variable like months and years

boreal umbra May 19, 2020, 5:29 PM

#

ah good point

#

though the hypothetical strfdelta method would just be for outputting a visual representation; the timedelta itself would be precise.

peak spoke May 19, 2020, 5:31 PM

#

datetime's strftime should end up going to time's strftime

#

and I don't believe there's a python implementation for time

boreal umbra May 19, 2020, 5:32 PM

#

You're right, the strftime method written in pure Python is actually just preparing an input for _time

peak spoke May 19, 2020, 5:39 PM

#

reminded me of an issue that points to how horrible the docstring on strftime is - "Format using strftime()."

boreal umbra May 19, 2020, 5:41 PM

#

I don't envy whoever was put in charge of that

#

The people on the various Python podcasts have remarked a few times that they always have to look up the syntax for datetime formatting.

peak spoke May 19, 2020, 5:43 PM

#

datetime could use a redo with how it's structured, but that would break a lot of things

#

Guessing it's one of the old libs

flat gazelle May 19, 2020, 5:46 PM

#

make datelib maybe, like pathlib

peak spoke May 19, 2020, 5:46 PM

#

well the first commit on gh is 30 years old

boreal umbra May 19, 2020, 5:58 PM

#

gh?

peak spoke May 19, 2020, 5:58 PM

#

github, sorry

#

ah, looked at the wrong module because an issue mislead me; the first commit there is 18 years old and looks like it was somewhere before

boreal umbra May 19, 2020, 6:07 PM

#

I should have been able to infer that you were talking about github

undone hare May 19, 2020, 6:27 PM

#

They weren't even using git at this time hehe

grave jolt May 19, 2020, 7:23 PM

#

wikipedia says that git was released in 2005, so...

#

So they probably weren't using it 18 years ago.

peak spoke May 19, 2020, 7:25 PM

#

Could've used something else for version control before, they didn't just make up the dates of the commits

true ridge May 19, 2020, 7:27 PM

#

before git, there was mercurial (before 2015~)

undone hare May 19, 2020, 7:58 PM

#

There's still a mercurial mirroir, if you're still living in the 90s too 😄

grizzled vigil May 19, 2020, 9:03 PM

#

Yep, for version control systems I believe CPython's history has been CVS -> SVN -> Mercurial -> Git

lost nexus May 19, 2020, 9:05 PM

#

Does python support pattern binding in variables? For example:

overwrites.send_messages, overwrites.add_reactions = False, False

flat gazelle May 19, 2020, 9:05 PM

#

Ye, that will work

#

We call it unpacking

lost nexus May 19, 2020, 9:06 PM

#

I see, alr.

rich wharf May 19, 2020, 9:10 PM

#

x = y => (
  if True:
    print(y)
)```

#

Example syntax for my concept of better python lambdas

#

It's unlikely for this to ever be added though

flat gazelle May 19, 2020, 9:11 PM

#

How do you deal with indentation within indented blocks?

rich wharf May 19, 2020, 9:11 PM

#

The syntax is as follows

#

( your block )

#

the inner block inside of indented blocks can be ignored up until the first statement

#

and the new lines after parentheses are encouraged

#

if not required

#

=> (
if True:
  print(5)
)
=> (
  if False:
    print(2)
)
=> (
      if False:
        print(3)
)

#

these are all valued

#

the second one is preferred

flat gazelle May 19, 2020, 9:13 PM

#

if True:
    x = y => (
if True:
    return False
)
```this is valid then?

rich wharf May 19, 2020, 9:13 PM

#

technically

#

but it's not preferred syntax

#

if True:
    x = y => (
      if True:
        return False
    )

#

My concept is that this is best practice

#

With the lambda indented one more then the outer layer

#

The good thing with surrounding this with parantheses means your example can also be parsed though

flat gazelle May 19, 2020, 9:17 PM

#

So this would be valid then

x = y => (
    6
)

#

You would probably want -> to avoid ambiguity with the => operator

slim island May 19, 2020, 9:24 PM

#

Some people are very opposed to pretty lambdas in Python

rich wharf May 19, 2020, 9:34 PM

#

Huh, sure -> works too

#

@flat gazelle For multi-line expressions, that syntax is valid

#

But for single expressions, just do

#

x = y -> 6

flat gazelle May 19, 2020, 9:35 PM

#

Actually NVM, the operator is >= and <=, not =>

#

Am doing a silly

rich wharf May 19, 2020, 9:35 PM

#

Well -> could be confused

#

=> could be confused with them

#

So -> is equally fine

rich wharf May 19, 2020, 10:11 PM

#

Also, we could keep existing lambdas for backwards compatibility

#

lambda: 5 <-- Still valid

#

-> 5 <-- Better practice

slim island May 19, 2020, 10:21 PM

#

or just introduce them in Python 4 and ditch the old way

lost nexus May 19, 2020, 11:19 PM

#

Which sequences in Python are fixed-size?

true ridge May 19, 2020, 11:20 PM

#

builtins: frozenset, tuple

peak spoke May 19, 2020, 11:21 PM

#

(byte)strings, range

true ridge May 19, 2020, 11:24 PM

#

mapping proxies are also frozen

magic python May 19, 2020, 11:24 PM

#

we're using R syntax in python now? 🤔

peak spoke May 19, 2020, 11:25 PM

#

are those builtin @true ridge ?

#

never really saw them beyond __dict__

true ridge May 19, 2020, 11:26 PM

#

well, technically yes type(type.__dict__) can give you access, but it isn't in the builtins module

peak spoke May 19, 2020, 11:27 PM

#

Guess they have a similiar use to a memoryview?

#

Haven't found a use for those yet, but neither did I exactly consider them

true ridge May 19, 2020, 11:28 PM

#

Also there is a named-tuple like sequence called PyStructSequence, that enpoweres sys.version_info etc. It is also embedded to language, but not accessible from the python level

peak spoke May 19, 2020, 11:30 PM

#

Oh is that what sys.flags uses? It claims to be a namedtuple in the docs but the features don't agree

true ridge May 19, 2020, 11:30 PM

#

from read-only proxy point of view, yea they both are similiar

#

yup @peak spoke

peak spoke May 19, 2020, 11:31 PM

#

that got me confused for a bit

true ridge May 19, 2020, 11:35 PM

#

it isn't efficient to use namedtuple in the C level, so this is kind a replacement to it but a bit different

peak spoke May 19, 2020, 11:36 PM

#

Does it have some normal documentation or only as a part of the c api docs?

#

If it's there at all

true ridge May 19, 2020, 11:38 PM

#

https://docs.python.org/3/c-api/tuple.html#struct-sequence-objects

boreal umbra May 19, 2020, 11:53 PM

#

Which file in the cpython repo parses command line arguments given to python?

#

looks like it might be this one: https://github.com/python/cpython/blob/master/Python/pythonrun.c

GitHub

python/cpython

The Python programming language. Contribute to python/cpython development by creating an account on GitHub.

true ridge May 20, 2020, 12:10 AM

#

It is a multi-layered process, but it startswith Modules/main.c:pymain_init

#

then you need to follow through the function calls, there are plenty of them

boreal umbra May 20, 2020, 12:10 AM

#

Thanks for letting me know!

#

Out of curiosity, how did you get the community role?

true ridge May 20, 2020, 12:11 AM

#

Out of curiosity, how did you get the community role?

I work on CPython on regular basis

boreal umbra May 20, 2020, 12:13 AM

#

That's pretty cool. My friend who hates Python was complaining to me that his code that would refuse to compile in Java runs in Python and gives him an attribute error, whereas he'd prefer to know at compile time where he messed up.

#

I was going to see what it would take to add a flag that runs the mypy linter and refuse to run if there's an issue there, with no pretense that it would get added to the language.

true ridge May 20, 2020, 12:14 AM

#

That is a cool idea, I just started like this. Thinked about a feature I would want, and implemented it while I was learning the internals

#

FWIW, it was a new conversion for f-strings for path expensions, f"{a!p}" => f"{os.fspath(a)}"

boreal umbra May 20, 2020, 12:15 AM

#

A few weeks ago I implemented my own variation on defaultdict, but I mostly copied the defaultdict implementation and made I think one notable change.

true ridge May 20, 2020, 12:16 AM

#

I saw it in the #esoteric-python

boreal umbra May 20, 2020, 12:16 AM

#

Sorry, I'm not sure what you're referring to about f-strings? That's something that you implemented?

true ridge May 20, 2020, 12:16 AM

#

that is what I thought would be cool to have, and implemented just for fun

boreal umbra May 20, 2020, 12:17 AM

#

But it got integrated? That's great!

true ridge May 20, 2020, 12:17 AM

#

no, it didn't

boreal umbra May 20, 2020, 12:17 AM

#

oh 😛

true ridge May 20, 2020, 12:17 AM

#

hahaha

boreal umbra May 20, 2020, 12:17 AM

#

I know how you feel.

true ridge May 20, 2020, 12:17 AM

#

but on the good side, it led me to contributing

boreal umbra May 20, 2020, 12:19 AM

#

By the way, I want to add my dict thing to pypi. I didn't see anything similar there when I looked. Should I explicitly state in the source code that I mostly copied it from the stdlib? I'm not trying to keep it a secret that I wrote almost none of it, but I don't know what the procedure is there.

true ridge May 20, 2020, 12:21 AM

#

By the way, I want to add my dict thing to pypi. I didn't see anything similar there when I looked. Should I explicitly state in the source code that I mostly copied it from the stdlib? I'm not trying to keep it a secret that I wrote almost none of it, but I don't know what the procedure is there.
@boreal umbra well, you can if you want, but for something like that there are no restrictions.

boreal umbra May 20, 2020, 12:22 AM

#

hmm I see

true ridge May 20, 2020, 12:24 AM

#

For an example, in the past, there was a tool in cpython repo itself (but not exposed in the stdlib) for unparsing an AST back to the source (and we've exposed it with 3.9 btw, ast.unparse) and someone directly took the source code and published on PyPI. For situations like that, you need to include PSFL in your license statement: https://github.com/simonpercivall/astunparse

GitHub

simonpercivall/astunparse

An AST unparser for Python. Contribute to simonpercivall/astunparse development by creating an account on GitHub.

boreal umbra May 20, 2020, 12:36 AM

#

One of the things I never learned in my one C class is where import statements are getting things from.

#

I guess "include statements" is more accurate in the context of C.

#

not sure though

prime estuary May 20, 2020, 12:38 AM

#

There's an "include path", which is a list of folders it searches through. <> means to use these system locations. "" means to search relative to the current folder.

boreal umbra May 20, 2020, 12:38 AM

#

aha

prime estuary May 20, 2020, 12:39 AM

#

Python has a similar system - sys.path.

boreal umbra May 20, 2020, 12:40 AM

#

I just tried that in a repl I happened to have running. I guess that's a list of directories it tries to import from in a __mro__ type way?

deft pagoda May 20, 2020, 6:53 AM

#

importing specific files in python is annoying

#

i don't know what the "right" way is, but i usually os.chdir for it

trail willow May 20, 2020, 7:08 AM

#

I am importing for example txt files pdf and excel with this f = open("demofile.txt", "r")

wide shuttle May 20, 2020, 7:09 AM

#

Hello @trail willow, this channel is for discussing the Python programming language itself, but we do have many other channels where you can ask a question.

#

If it's short or more general, there's #python-discussion, but otherwise you can claim a help channel for you question. The information for how to do that is in #❓｜how-to-get-help

undone hare May 20, 2020, 7:10 AM

#

i don't know what the "right" way is, but i usually os.chdir for it
@deft pagoda the right way :

p = '/home/usr/myfile.py'
with open(p) as f:
    exec(f.read())```works like a charm haha

deft pagoda May 20, 2020, 7:10 AM

#

i've thought about adding a similar function to ipython

dusty haven May 20, 2020, 8:13 AM

#

Importlib can do that no?

gray mirage May 20, 2020, 8:16 AM

#

Well there's execfile

deft pagoda May 20, 2020, 8:17 AM

#

there's reload from importlib which i use often, but it won't work if you just import specific objects

sacred tinsel May 20, 2020, 8:20 AM

#

I use reload when testing modules in a jupyter session

#

works great for me

deft pagoda May 20, 2020, 8:21 AM

#

try it when doing from x import y

sacred tinsel May 20, 2020, 8:21 AM

#

yeah you have to get it from the module

#

but it's not difficult to account for, right?

#

you can do

#

reload(x); y = x.y

deft pagoda May 20, 2020, 8:22 AM

#

you can do that

#

it's annoying though, i should just overload reload

true ridge May 20, 2020, 8:24 AM

#

@dusty haven yep, you can create a spec from the path and then execute that spec to get a module object.

deft pagoda May 20, 2020, 8:29 AM

#

does this look right:

def reload(obj):
    if hasattr(obj, '__spec__'): return importlib.reload(obj)

    try:
        module = importlib.reload(globals()[obj.__module__])
    except KeyError:
        module = importlib.import_module(obj.__module__)

    globals()[obj.__name__] = getattr(module, obj.__name__)

unkempt rock May 20, 2020, 9:25 AM

#

OK

dire hull May 20, 2020, 9:56 AM

#

Petition to change loop to using index instead of iter in python4

deft pagoda May 20, 2020, 9:56 AM

#

👎

dire hull May 20, 2020, 9:57 AM

#

adapride

#

Why can't it be like normal langs

deft pagoda May 20, 2020, 9:57 AM

#

because then people wouldn't use it

dire hull May 20, 2020, 9:57 AM

#

Wat why

wide shuttle May 20, 2020, 9:57 AM

#

A foreach-style loop isn't that uncommon and Python isn't the first to use this direct iteration style

#

I don't really see the advantage in iterating over integers if I want the elements of something

undone hare May 20, 2020, 9:58 AM

#

That would be just too much verbose

dire hull May 20, 2020, 9:58 AM

#

Can you gib example of another language that has this?

deft pagoda May 20, 2020, 9:58 AM

#

the boilerplate setup of for-loops in c is so much worse

wide shuttle May 20, 2020, 9:58 AM

#

"Hey, let's iterate over those integer range here. Why? Well, I want the elements of that other thing, but I decided to strip out the feature that allows me to do that, so let's do it in this roundabout way"

dire hull May 20, 2020, 9:59 AM

#

Yes cuz index are somewhat independent of the content of the collection of things

#

And if I want to skip something I could just set it to skip

#

That's great I think

wide shuttle May 20, 2020, 9:59 AM

#

A more fundamental restriction is that most iterables in Python don't even have an index

deft pagoda May 20, 2020, 9:59 AM

#

this

dire hull May 20, 2020, 9:59 AM

#

Hum

#

I see

#

I ve only used list matrix and nested lists and dict so far lol

wide shuttle May 20, 2020, 10:00 AM

#

Yes cuz index are somewhat independent of the content of the collection of things
@dire hull

No, you're making your iteration depend on more context and be more restrictive as well

deft pagoda May 20, 2020, 10:00 AM

#

dicts don't have an index

dire hull May 20, 2020, 10:00 AM

#

Yes

deft pagoda May 20, 2020, 10:00 AM

#

if you're iterating over a dict, an index does not help

dire hull May 20, 2020, 10:00 AM

#

They fast I liek that

#

So basically python loop is better than C loop?

deft pagoda May 20, 2020, 10:01 AM

#

it's different

wide shuttle May 20, 2020, 10:01 AM

#

It's different

deft pagoda May 20, 2020, 10:01 AM

#

ginx

dire hull May 20, 2020, 10:01 AM

#

So which is better then

wide shuttle May 20, 2020, 10:02 AM

#

I like Python-style iteration, but it fits the philosophy of abstraction

#

I want to iterate over the items of this list, so let's iterate over the items of this list

#

The index of the items has nothing to do with it

dire hull May 20, 2020, 10:02 AM

#

I see

#

What I meant by they are somewhat independent is that you could make them dependant or if you need them to be separate you could do that as well

#

So essentially you could alter the loop search method somehow

wide shuttle May 20, 2020, 10:03 AM

#

I don't know what you mean by that, but if you want to enumerate your iterable as you get elements from it, you can do that already

dire hull May 20, 2020, 10:03 AM

#

Yeah salt die showed me

wide shuttle May 20, 2020, 10:03 AM

#

And, the upshot is, enumerate works with iterables that don't allow indexing with an integer

deft pagoda May 20, 2020, 10:04 AM

#

you can make wacky iterables in python where indices won't really help you:

In [21]: class MyIter: 
    ...:     def __iter__(self): 
    ...:         yield 'this' 
    ...:         yield 'is' 
    ...:         yield 'insane' 
    ...:                                                                                                                            

In [22]: for i in MyIter(): 
    ...:     print(i) 
    ...:                                                                                                                            
this
is
insane

flat gazelle May 20, 2020, 10:04 AM

#

C style for loops do have their merits, but not in the pure for(int i = 0; i < 20; i++) form

dire hull May 20, 2020, 10:04 AM

#

So what they good at ?

flat gazelle May 20, 2020, 10:05 AM

#

they are neat when you put something else into those conditions, for example

#

for(int i = 1; i < num; i *= 2) {}

#

in python, you would need a while loop

dire hull May 20, 2020, 10:06 AM

#

Maybe I'm just used to change index in loops lol

#

adapride

#

Honestly I ve been using python for a while and never realized that for loops don't work like I thought

#

Tis kinda scary

flat gazelle May 20, 2020, 10:07 AM

#

another neat one is

for (int i = 0; i[some_string]; i++) {}
```to iterate over all indicies within a string

deft pagoda May 20, 2020, 10:07 AM

#

i feel like that should alias for with foreach or for each

dire hull May 20, 2020, 10:07 AM

#

Yes maybe stress it a bit

deft pagoda May 20, 2020, 10:08 AM

#

maybe that violates the there should be only one way

dire hull May 20, 2020, 10:08 AM

#

So that lazy peeps like me would know lol

flat gazelle May 20, 2020, 10:08 AM

#

but foreach loops are in pretty much in every modern language, though most also keep the C style for loops as an alternative

wide shuttle May 20, 2020, 10:08 AM

#

Iteration, iterables, and iterators are core concepts in Python and quite fundamental to how a lot of things work in the language

dire hull May 20, 2020, 10:09 AM

#

I'ma read on that lol

wide shuttle May 20, 2020, 10:09 AM

#

I don't think just changing the name would work, although it may help

#

At the same time, learning about the concepts is important on your way to reaching an intermediate level

dire hull May 20, 2020, 10:09 AM

#

Ye

#

I m still reluctant to read on high level funcs lol too much work it feels like

grave jolt May 20, 2020, 10:21 AM

#

Why does https://docs.python.org/3.9/ show 3.10 docs?

peak spoke May 20, 2020, 10:27 AM

#

hmm they seem to be really weird around that https://docs.python.org/3.9/whatsnew/3.9.html shows proper what's new but the release is 3.10 in the header (and why do the releases show current date ?)

true ridge May 20, 2020, 10:28 AM

#

well, probably a regex bug

#

https://github.com/python/cpython/blob/3.9/Doc/tools/static/switchers.js#L4-L10 this might be the problem, not sure though

GitHub

python/cpython

The Python programming language. Contribute to python/cpython development by creating an account on GitHub.

mellow rapids May 20, 2020, 10:31 AM

#

how would i know what module to import for each project

#

thats smth i struggle with

#

and what happens if you dont import any module and just start coding

#

and how does the code know how to do each function

#

like do i just write them out in english in the correct template

#

like bird.move(cdvevee)

#

thx

dire hull May 20, 2020, 10:36 AM

#

You need to know what function you are using I think

flat gazelle May 20, 2020, 10:36 AM

#

you only import things once you discover you need sth from the given module

dire hull May 20, 2020, 10:36 AM

#

I didn't quite understand the question tbh

gloomy rain May 20, 2020, 10:37 AM

#

@mellow rapids The language has certain constructs and functions built into it, which you can use without importing anything.

#

There is also a standard module library that is bundled with Python, which can let you do a lot of things. If you need your program to do something that's not supported by the standard module library, you might be able to find third-party libraries online instead. In either case, you can usually find which module (whether it's bundled with Python or not) does what you want by googling.

#

@mellow rapids As for your bird.move() example, unless they happen to be built into the language, Python won't know what you mean by "bird" and "move" unless you define those names.

#

That could either mean typing out the definitions in your own code, or importing the names from a module (standard library or otherwise).

mellow rapids May 20, 2020, 10:42 AM

#

ohh okay
you can always google what module to use i guess
thank you

gloomy rain May 20, 2020, 10:43 AM

#

Yeah, I mean, if you need to, say, load a csv file from your computer, you could google "how to load csv in python"

#

And you will probably find a result that tells you about the csv module.

mellow rapids May 20, 2020, 10:44 AM

#

oki

true ridge May 20, 2020, 10:46 AM

#

@grave jolt would you open an issue?

#

that looks like a bug

wide shuttle May 20, 2020, 11:01 AM

#

Hey @fossil charm, this is not a help channel, but rather a channel to discuss the Python programming language itself. We do have a lot of help channels and you can claim one from the Python Help: Available category just above the category this channel is in. See #❓｜how-to-get-help for more details.

undone hare May 20, 2020, 11:16 AM

#

Why does https://docs.python.org/3.9/ show 3.10 docs?
future-proofing haha

radiant fulcrum May 20, 2020, 11:38 AM

#

If you switch using the toggle to 3.9 it dissapears

#

which then goes to 3.8

#

then you go back to 3.9, and get 3.10

#

lol

grave jolt May 20, 2020, 11:54 AM

#

They used 1-indexed lists

true ridge May 20, 2020, 11:57 AM

#

It is a bug, and should be reported

red solar May 20, 2020, 12:39 PM

#

@wide shuttle wait you can enumerate over sequences that don't have an integer index? so enumerate(dict) is basically for key, value in dict.items()?

flat gazelle May 20, 2020, 12:40 PM

#

no, enumerate gives any iterable sequential integer keys

red solar May 20, 2020, 12:40 PM

#

oh :/

wide shuttle May 20, 2020, 12:40 PM

#

It will enumerate the elements that come out

red solar May 20, 2020, 12:41 PM

#

eh ig that's cool too

full jay May 20, 2020, 12:41 PM

#

Saves you from having to implement it yourself

#

Which is always nice

lusty bramble May 20, 2020, 12:46 PM

#

i have a question about inheritance on immutable class, where can i ask it ?

full jay May 20, 2020, 12:46 PM

#

You can ask here if you like, since it's about a broad concept in Python

lusty bramble May 20, 2020, 12:47 PM

#

ok

oblique crystal May 20, 2020, 12:47 PM

#

hey @covert rain perhaps it beeter fits here, as it is no longer about a "how to achieve" but about what we actually achieve with python there

covert rain May 20, 2020, 12:48 PM

#

I believe it is already answered?

lusty bramble May 20, 2020, 12:49 PM

#

i want to make an inheritance class on numpy.ndarray. it does’nt work with init and i dont know enough about new to do it

red solar May 20, 2020, 12:51 PM

#

(not an aswer to the general concept of immutable inheritance, and i'm still wanna see the answer for that, but https://stackoverflow.com/questions/27910013/how-can-a-class-that-inherits-from-a-numpy-array-change-its-own-values seems like you can get a view and use that?)

oblique crystal May 20, 2020, 12:52 PM

#

like I said, we have found the solutions, but are they equivalent? @covert rain

📎 unknown.png

lusty bramble May 20, 2020, 12:53 PM

#

@red solar thanks !

#

i dont understand the .view(cls) but it works

covert rain May 20, 2020, 12:54 PM

#

"equivalent" is a loose term

peak spoke May 20, 2020, 12:54 PM

#

the partial calls it as a normal function with the instance passed while the get binds it normally

covert rain May 20, 2020, 12:54 PM

#

they are equivalent in the sense that they will do the same thing

#

in my opinion the functools.partial version is better because it is more readable

#

in the company I work for, we flag invocation of dunder methods for further code review

red solar May 20, 2020, 12:56 PM

#

what are dunder methods again?

#

__ stuff?

covert rain May 20, 2020, 12:56 PM

#

methods that start and end with two underscores

#

dunder - double under

red solar May 20, 2020, 12:56 PM

#

ah k

oblique crystal May 20, 2020, 12:57 PM

#

indeed. Or at least they seem to do the same thing.

peak spoke May 20, 2020, 12:57 PM

#

Yeah dunders should usually stay hidden behind some normal funcs that have the same behaviour or access them; but while I don't know the original issue, adding methods to instances after they were created doesn't sound very nice

oblique crystal May 20, 2020, 12:57 PM

#

but can partial lead to some side effects?

#

in a more complex case

covert rain May 20, 2020, 12:58 PM

#

yeah, suppose you have to pass this method to another code that inspects the method itself to find which class it is bound to

oblique crystal May 20, 2020, 12:58 PM

#

adding methods to instances after they were created doesn't sound very nice
we this is not for production or anything, it's for quick test/prtotypye

covert rain May 20, 2020, 12:58 PM

#

but that is evil over evil chain

deft pagoda May 20, 2020, 12:58 PM

#

am reminded of a beazley talk:

def __iter__(self):
    if not self.done():
        yield self
    return self.result()

Future.__iter__ = __iter__

flat gazelle May 20, 2020, 12:59 PM

#

you can trivially assign to the class, but here they are assigning to instances

covert rain May 20, 2020, 12:59 PM

#

they want it only in one instance

#

it doesn't make sense to want it to be a method

#

because it is not in the class anyway

#

so it can be a normal function

flat gazelle May 20, 2020, 1:00 PM

#

yeah, dont do poor style

#

inherit if you must

oblique crystal May 20, 2020, 1:00 PM

#

in short: I have a class in the module that I don't want to touch explicitly now and a code that works that uses it.
I want to replace one specific method with the other one that is in development. So rather than change the module every time and reload jupyter/ipython kernel etc (or redo the import) or to subclass I want just to change the specific method

covert rain May 20, 2020, 1:00 PM

#

yeah, so you're monkeypatching an instance

deft pagoda May 20, 2020, 1:00 PM

#

inheritance

covert rain May 20, 2020, 1:00 PM

#

just use partial

oblique crystal May 20, 2020, 1:00 PM

#

yes

deft pagoda May 20, 2020, 1:00 PM

#

just subclass it

covert rain May 20, 2020, 1:00 PM

#

it is a one-off thing

#

not a project

oblique crystal May 20, 2020, 1:01 PM

#

I don't want subclass it

covert rain May 20, 2020, 1:01 PM

#

you can just use whatever

oblique crystal May 20, 2020, 1:01 PM

#

because it is a big class and in init and later it needs to do the claculations

deft pagoda May 20, 2020, 1:01 PM

#

then monkey patch it, i don't know what your original ask was

flat gazelle May 20, 2020, 1:01 PM

#

just do

class InDevThing(Thing):
    def my_indev_method():...
```and just replace the instantiation

unkempt rock May 20, 2020, 1:01 PM

#

monkey patching sounds like the best option to me

flat gazelle May 20, 2020, 1:01 PM

#

ye, patching is also an option

red solar May 20, 2020, 1:01 PM

#

@lusty bramble __new__ creates an instance of your class - so when you call __new__, whatever it returns is now what you're referencing with self (i think). So then in updateNumpyArrayWithValues, self is obj that's returned by new - which is the array view

oblique crystal May 20, 2020, 1:01 PM

#

yeah I did not know the term monkey patching when I was asking

#

also I did not know how to monkey patch it better

covert rain May 20, 2020, 1:02 PM

#

they are monkey patching - the question is whether to monkey patch with functools.partial or with MyClass.__get__

#

I'd go with functools.partial all day

unkempt rock May 20, 2020, 1:02 PM

#

partial

lusty bramble May 20, 2020, 1:02 PM

#

@lusty bramble __new__ creates an instance of your class - so when you call __new__, whatever it returns is now what you're referencing with self (i think). So then in updateNumpyArrayWithValues, self is obj that's returned by new - which is the array view
@red solar ok

red solar May 20, 2020, 1:02 PM

#

why functools over get?

#

dislike dunder methods?

covert rain May 20, 2020, 1:03 PM

#

dunder methods are not meant to be called

wide shuttle May 20, 2020, 1:03 PM

#

You could use types.MethodType to create a bound method

covert rain May 20, 2020, 1:03 PM

#

you should only call them when you subclassed and you are calling the overriden method

#

otherwise, let python call them for you

wide shuttle May 20, 2020, 1:04 PM

#

!e

import types

def monkey_patch(self):
    print(self)

bound_method = types.MethodType(monkey_patch, "hello, there")
print(bound_method)
bound_method()

fallen slateBOT May 20, 2020, 1:04 PM

#

@wide shuttle :white_check_mark: Your eval job has completed with return code 0.

001 | <bound method monkey_patch of 'hello, there'>
002 | hello, there

oblique crystal May 20, 2020, 1:04 PM

#

oh

#

ok so types.MethodType is equivalent to dunder get basically?

covert rain May 20, 2020, 1:05 PM

#

default dunder get implementation calls types.MethodType

#

but you could have a metaclass that does something else

oblique crystal May 20, 2020, 1:06 PM

#

no metaclasses here (don't even know what are those 😁 )

#

Ves, where is the instance in your example btw? 🙂

deft pagoda May 20, 2020, 1:07 PM

#

the string

wide shuttle May 20, 2020, 1:08 PM

#

It's the string, yes

covert rain May 20, 2020, 1:09 PM

#

types.MethodType does roughly the same as functools.partial

#

I would still go with functools.partial

oblique crystal May 20, 2020, 1:11 PM

#

I see. So with types in my example it would be

#

!e

import types
class A:
    def __init__(self,b):
        self.b = b
    def print_b(self):
        print(self.b)
a=A(5)
a.print_b()
def print_b_2(self):

    print(self.b**2)
a.print_b_2 = types.MethodType(print_b_2,a)
a.print_b_2()
print(a.print_b_2)
dis.dis('a.print_b_2()')```

fallen slateBOT May 20, 2020, 1:11 PM

#

You are not allowed to use that command here. Please use the #bot-commands channel instead.

oblique crystal May 20, 2020, 1:11 PM

#

oh crap, I forgot I can't do it here

deft pagoda May 20, 2020, 1:11 PM

#

yeah, that will work i think

#

In [2]: import types 
   ...:  
   ...: def monkey_patch(self): 
   ...:     print('hi') 
   ...:  
   ...: class Test: ... 
   ...:  
   ...: test = Test() 
   ...: test.say_hi = types.MethodType(monkey_patch, test) 
   ...: test.say_hi()                                                                                                               
hi

oblique crystal May 20, 2020, 1:12 PM

#

yeah just tested.
Btw if you do dis.dis on the monkey patching line the dunder method has one less call

#

📎 unknown.png

#

vs

📎 unknown.png

unkempt rock May 20, 2020, 1:13 PM

#

oh, check it out, the functools.partial signature is using a positional only parameter. that's actually a good example for its use-case

functools.partial(func, /, *args, **keywords)

deft pagoda May 20, 2020, 1:15 PM

#

In [7]: ThreadPoolExecutor.submit?                                                                                                  
Signature: ThreadPoolExecutor.submit(self, fn, /, *args, **kwargs)

#

same deal

oblique crystal May 20, 2020, 1:17 PM

#

ok thanks everyone for suggestion on monkey patching 🙂 now time to actually use it

grave jolt May 20, 2020, 2:11 PM

#

@unkempt rock yes, that's a very good example, because a function can have a func kwarg

full jay May 20, 2020, 3:01 PM

#

I feel like I relearn about functools almost daily

deft pagoda May 20, 2020, 3:27 PM

#

did yall know about re.Scanner

#

In [51]: tokens = ['(?P<NUMBER>\d+)', 
    ...:           '(?P<PLUS>\+)', 
    ...:           '(?P<MINUS>-)', 
    ...:           '(?P<WS>\s+)'] 
    ...: m = re.compile('|'.join(tokens)) 
    ...: s = m.scanner('1 + 2 - 3') 
    ...: list(iter(s.match, None))                                                                                                  
Out[51]: 
[<re.Match object; span=(0, 1), match='1'>,
 <re.Match object; span=(1, 2), match=' '>,
 <re.Match object; span=(2, 3), match='+'>,
 <re.Match object; span=(3, 4), match=' '>,
 <re.Match object; span=(4, 5), match='2'>,
 <re.Match object; span=(5, 6), match=' '>,
 <re.Match object; span=(6, 7), match='-'>,
 <re.Match object; span=(7, 8), match=' '>,
 <re.Match object; span=(8, 9), match='3'>]

cloud crypt May 20, 2020, 4:04 PM

#

@deft pagoda looks like finditer to me

hasty thistle May 20, 2020, 4:05 PM

#

that seems really similar to re.finditer...
I like some other examples I found though, with converting int/float and recognizing simple operators for example

>>> scanner.scan("sum = 3*foo + 312.50 + bar")
(['sum', "<OPCODE>'='", 3, "<OPCODE>'*'", 'foo', "<OPCODE>'+'", 312.5, "<OPCODE>'+'", 'bar'], '')

cloud crypt May 20, 2020, 4:06 PM

#

seems interesting

grave jolt May 20, 2020, 4:08 PM

#

!e

import re

def tokenize(tokens, string):
    matches = iter(re.compile("|".join(tokens)).scanner(string).match, None)
    tokens = ((k := next(filter(m.group, m.groupdict())), m.group(k)) for m in matches)
    return tokens

for token in tokenize(['(?P<NUMBER>\d+)', '(?P<PLUS>\+)'], "1+42+3"):
    print(token)

fallen slateBOT May 20, 2020, 4:08 PM

#

@grave jolt :white_check_mark: Your eval job has completed with return code 0.

001 | ('NUMBER', '1')
002 | ('PLUS', '+')
003 | ('NUMBER', '42')
004 | ('PLUS', '+')
005 | ('NUMBER', '3')

hasty thistle May 20, 2020, 4:24 PM

#

don't see why you'd use scanner there, when re.finditer does the job as well (this has the exact same output for me)

def tokenize(tokens, string):
    matches = re.finditer('|'.join(tokens), string)
    tokens = ((k, m.group()) for m in matches for k, v in m.groupdict().items() if v)
    return tokens

unkempt rock May 21, 2020, 7:16 PM

#

the future ~

#

https://www.youtube.com/watch?time_continue=159&v=fZSFNUT6iY8&feature=emb_title

YouTube

Fazil Babu

OpenAI Model Generates Python Code

Full Video: https://www.pscp.tv/Microsoft/1OyKAYWPRrWKb?t=29m19s
Credits: Microsoft, OpenAI

▶ Play video

#

this goes a step beyond normal code completion, it generates snippets based on comments

inland acorn May 21, 2020, 8:26 PM

#

first we made code to steal others jobs, now we are writting code to steal our own job?!

flat gazelle May 21, 2020, 8:28 PM

#

type driven development, but the types are just english text

torn yacht May 21, 2020, 9:31 PM

#

@inland acorn haha

inland acorn May 21, 2020, 9:32 PM

#

the next step is writting code, that writes ai that writes code

boreal umbra May 21, 2020, 11:58 PM

#

@deft pagoda is re.Scanner supposed to emulate Java.util.Scanner?

#

Because the Java scanner is my least favorite OOP solution that's ever been invented.

deft pagoda May 22, 2020, 12:35 AM

#

i doin't know what that is

#

all i know is that re.scanner is undocumented

#

it's a re secret

torn yacht May 22, 2020, 12:45 AM

#

the next step is writting code, that writes ai that writes code
@inland acorn Then writing code that writes code that writes code

unkempt rock May 22, 2020, 12:47 AM

#

a code that writes itself
hmm

unkempt rock May 22, 2020, 1:28 AM

#

hmm.....

dusty haven May 22, 2020, 3:17 AM

#

That's just a compiler

unkempt rock May 22, 2020, 4:15 AM

#

no an ai that writes itself over and over again i think

unkempt rock May 22, 2020, 5:02 AM

#

How about an ai that creates an ai to then have them work on eachother to improve constantly

dire hull May 22, 2020, 5:03 AM

#

So GAN

unkempt rock May 22, 2020, 5:04 AM

#

Basically

limpid umbra May 22, 2020, 1:23 PM

#

height = no.round(np.random.normal(1.75, 0.20, 5000), 2)

What does the last 2 stand for?
What's is the function of the "2" here?

unkempt rock May 22, 2020, 1:23 PM

#

wrong channel but it's to round up to 2 decimals

limpid umbra May 22, 2020, 1:23 PM

#

Oh, Thanks

shy vine May 22, 2020, 1:52 PM

#

@glad goblet This is a channel for the discussion of the python language

glad goblet May 22, 2020, 1:52 PM

#

oh ok

unkempt rock May 22, 2020, 2:02 PM

#

what is b-string ?

deft pagoda May 22, 2020, 2:02 PM

#

a byte string

unkempt rock May 22, 2020, 2:03 PM

#

and what is libpython3.7m.so.1.0 ?

deft pagoda May 22, 2020, 2:04 PM

#

looks like some shared object file

unkempt rock May 22, 2020, 2:04 PM

#

seems like a library to me

#

library "libpython3.7m.so.1.0" not found

deft pagoda May 22, 2020, 2:04 PM

#

.so is shared object extension

#

it's a c-extension for something

gentle lodge May 22, 2020, 2:07 PM

#

yeah on windows they call them "DLLs"

round nexus May 22, 2020, 2:56 PM

#

did anyone have a problem with python-dotenv where some env var names could not be fetched? like the word DEBUG is not being fetched for some reason, but if I rename it to say HELLO, then i get an output

unkempt rock May 22, 2020, 2:57 PM

#

the word debug might be a reserved name for something

round nexus May 22, 2020, 2:58 PM

#

oh

unkempt rock May 22, 2020, 2:58 PM

#

i don't know.

#

i'm just guessing

round nexus May 22, 2020, 2:58 PM

#

could be

unkempt rock May 22, 2020, 2:59 PM

#

is it possible there is a global variable DEBUG it is fetching?

#

but it's empty or something?

round nexus May 22, 2020, 2:59 PM

#

nop

#

empty

unkempt rock May 22, 2020, 3:00 PM

#

external system variable i mean

#

environment variable

#

or maybe the software was started with a flag DEBUG

#

those could be some of the reasons why it's not letting you override it?

shy vine May 22, 2020, 3:02 PM

#

This would probably be better in a help channel, this is a channel for Python language discussion

round nexus May 22, 2020, 3:03 PM

#

I mean its a general discussion, not a question

shy vine May 22, 2020, 3:03 PM

#

This isn’t a general discussion channel

round nexus May 22, 2020, 3:03 PM

#

okay

unkempt rock May 22, 2020, 3:34 PM

#

general is getting raided

tough moat May 22, 2020, 3:34 PM

#

rip

#

I was having a nice discussion

uncut sage May 22, 2020, 3:58 PM

#

@tough moat in re your question, the most common thing to do is include a requirements.txt file with the repo, or a proper setup.py

molten onyx May 22, 2020, 4:17 PM

#

You also have the option of pyproject.toml now

#

https://www.python.org/dev/peps/pep-0518/

Python.org

PEP 518 -- Specifying Minimum Build System Requirements for Python ...

The official home of the Python Programming Language

unkempt rock May 22, 2020, 4:22 PM

#

so ik this isnt the place to ask this but general is locked soo yeah,Im still gonna ask,Does anyone know a server like this one just for java script

surreal fern May 22, 2020, 4:22 PM

#

Hello guys need help regarding setting environment variable in virutalenv on windows machine I tried set PYTHONPATH="TESTSTRING" but when I print(os.environ["PYTHONPATH"]) It give raise KeyError(key) from None

gray mirage May 22, 2020, 4:24 PM

#

The general channel was locked while staff deal with a raid

modern frigate May 22, 2020, 4:24 PM

#

Oh

gray mirage May 22, 2020, 4:24 PM

#

If you need help, see #❓｜how-to-get-help

crystal quarry May 22, 2020, 4:24 PM

#

@unkempt rock Sorry, no, I don't, but it's JavaScript, one word.

gray mirage May 22, 2020, 4:24 PM

#

If you want to discuss something off topic,

modern frigate May 22, 2020, 4:25 PM

#

What happened?

gray mirage May 22, 2020, 4:25 PM

#

!off-topic

fallen slateBOT May 22, 2020, 4:25 PM

#

Off-topic channels

There are three off-topic channels:
• #ot0-psvm’s-eternal-disapproval
• #ot1-perplexing-regexing
• #ot2-never-nester’s-nightmare

Their names change randomly every 24 hours, but you can always find them under the OFF-TOPIC/GENERAL category in the channel list.

modern frigate May 22, 2020, 4:25 PM

#

kk

crystal quarry May 22, 2020, 4:25 PM

#

@unkempt rock And it's completely unrelated to Java FYI

gray mirage May 22, 2020, 4:25 PM

#

Ah, speak of the devil, #python-discussion has been unlocked.

crystal quarry May 22, 2020, 4:26 PM

#

Someone wrote some bot to spam general. That is what happened.

gray mirage May 22, 2020, 4:26 PM

#

Let's get back on topic.

unkempt rock May 22, 2020, 4:26 PM

#

Ah, speak of the devil, #python-discussion has been unlocked.
@gray mirage oh ok,Thanks

sudden briar May 22, 2020, 5:04 PM

#

Anyone who checked this open source book on python?
http://openbookproject.net/thinkcs/python/english3e/index.html

#

It's awesome!

obsidian prawn May 22, 2020, 7:48 PM

#

what non-library features of python would people consider required for it to be useable?

flat gazelle May 22, 2020, 7:48 PM

#

nothing really. You can do a lot in python with just vim and the basic install

#

for larger projects, you do want some linter, code formatter and type checker

worldly venture May 22, 2020, 8:20 PM

#

a

deft pagoda May 22, 2020, 8:27 PM

#

i have none of those things! i consider numpy essential though

#

and networkx

obsidian prawn May 22, 2020, 8:58 PM

#

i guess what i should say is what functions of base python are considered essential, stuff like functions, imports, etc.

flat gazelle May 22, 2020, 9:02 PM

#

All of it except like... The walrus operator, filter, map.

deft pagoda May 22, 2020, 9:03 PM

#

map is offended

pliant tusk May 22, 2020, 9:06 PM

#

map = lambda f,l,*i:(f(*q) for q in zip(l,*i)) map is trivial to re-implement

inland acorn May 22, 2020, 9:08 PM

#

map might be one of my favorite functions xD

deft pagoda May 22, 2020, 9:11 PM

#

i think you implemented starmap

pliant tusk May 22, 2020, 9:12 PM

#

that up there works the same as map

#

filter = lambda f, i:(q for q in i if (f or (lambda q:q))(q)) filter was a bit weirder to do in oneline

flat gazelle May 22, 2020, 9:15 PM

#

To be nitpicky, map(f) is an error with python and an empty iterator with your version.

pliant tusk May 22, 2020, 9:15 PM

#

fixed it

inland acorn May 22, 2020, 9:16 PM

#

you are right! we dont need any functions, all we need are lambdas and generator expressions!

pliant tusk May 22, 2020, 9:16 PM

#

imo most builtins are rewritable with listcomps and lambdas

deft pagoda May 22, 2020, 9:16 PM

#

map = lambda f, i:(f(q) for q in i)

does this not work

pliant tusk May 22, 2020, 9:17 PM

#

map can take multiple iterables for funcs that take more than one argument

#

map(lambda a,b:a+b, [1,2,3], [3,2,1])

deft pagoda May 22, 2020, 9:18 PM

#

oh, i always use starmap over a zip

#

figures

pliant tusk May 22, 2020, 9:19 PM

#

lol starmap(f, i) == map(f, *i)

deft pagoda May 22, 2020, 9:19 PM

#

isn't it beautiful

pliant tusk May 22, 2020, 9:19 PM

#

map is always beautiful

#

also i didnt realize until now that filter(None, iterable) was a thing

#

it just checks the truthiness of each element in the iterable in that case

deft pagoda May 22, 2020, 9:21 PM

#

it's (x for x in iterable if x)?

pliant tusk May 22, 2020, 9:21 PM

#

yea

deft pagoda May 22, 2020, 9:21 PM

#

can you just pass in one argument in that case

#

like filter(iterable)

pliant tusk May 22, 2020, 9:22 PM

#

no

#

it needs None or a func

deft pagoda May 22, 2020, 9:23 PM

#

isn't there a itertools function that does that

pliant tusk May 22, 2020, 9:24 PM

#

probably

deft pagoda May 22, 2020, 9:25 PM

#

oh, i was thinking of compress, but then you'd need compress(iterable, iterable)

inland acorn May 22, 2020, 9:28 PM

#

I give you abs with no function calls (returns a string)```py
abs = lambda n: (o:="",x:=True, [o:=o+i for i in f"{n}" if ("0"<=i<="9" and x,(x:=False) if i=="."else None)[0]],o)[-1]

#

and there is the mathy version xD ```py
abs = lambda n: (n*n)**.5 // 1

deft pagoda May 22, 2020, 9:33 PM

#

can you use max

inland acorn May 22, 2020, 9:33 PM

#

that would work max(n, n*-1)

pliant tusk May 22, 2020, 9:33 PM

#

abs = lambda n:f'{n:+}'[1:]

deft pagoda May 22, 2020, 9:33 PM

#

max(n, -n)

pliant tusk May 22, 2020, 9:34 PM

#

you can always abuse fstrings

inland acorn May 22, 2020, 9:34 PM

#

what does the + option do?

pliant tusk May 22, 2020, 9:34 PM

#

always shows +n or -n

inland acorn May 22, 2020, 9:34 PM

#

ah

#

would still need to remove the part after . tho

pliant tusk May 22, 2020, 9:35 PM

#

nah

deft pagoda May 22, 2020, 9:35 PM

#

next(next({n, -n})) if sets are ordered for ints

pliant tusk May 22, 2020, 9:35 PM

#

that option works with floats

deft pagoda May 22, 2020, 9:36 PM

#

shit, i'm calling next on an int

inland acorn May 22, 2020, 9:36 PM

#

In [3]: abs = lambda n:f'{n:+}'[1:]            

In [4]: abs(-5.5)      
Out[4]: '5.5'``` well `abs` should return `5` on that right?

#

wait no

#

what am I thinking

#

my brain just went to a completly wrong place xD

#

for some reason I tought abs always returned a int 🙃

modern night May 22, 2020, 9:37 PM

#

i mean its not as elegant but u can just do python abs = lambda x: x if x > 0 else -x

pliant tusk May 22, 2020, 9:38 PM

#

wow we are dumb

modern night May 22, 2020, 9:38 PM

#

also preserves type

pliant tusk May 22, 2020, 9:38 PM

#

youre right

#

abs = lambda x:(x,-x)[x<0]

inland acorn May 22, 2020, 9:38 PM

#

abs = lambda x:[x,-x][x<0]```

deft pagoda May 22, 2020, 9:39 PM

#

use a tuple

unkempt rock May 22, 2020, 9:39 PM

#

Hmm, this is new to me

#

this is using an Array?

deft pagoda May 22, 2020, 9:40 PM

#

yep

unkempt rock May 22, 2020, 9:40 PM

#

I see, that looks really weird

grave jolt May 22, 2020, 9:40 PM

#

!e

abs = lambda x:[*{x,-x}][0]
print(abs(3.14))
print(abs(-3.14))
print(abs(0))

fallen slateBOT May 22, 2020, 9:40 PM

#

@grave jolt :white_check_mark: Your eval job has completed with return code 0.

001 | 3.14
002 | 3.14
003 | 0

inland acorn May 22, 2020, 9:40 PM

#

it is not something you would use in real code

unkempt rock May 22, 2020, 9:40 PM

#

Sorry mate, i tend to be a java guy than a python lol

#

or C++

grave jolt May 22, 2020, 9:40 PM

#

oh, salt-die already had a setful solution

inland acorn May 22, 2020, 9:40 PM

#

this is getting into werid python land, ( #esoteric-python )

deft pagoda May 22, 2020, 9:41 PM

#

yeah, this is getting esoteric

pliant tusk May 22, 2020, 9:41 PM

#

a bit

unkempt rock May 22, 2020, 9:41 PM

#

is it as same as adding the variable into an Arraylist?

inland acorn May 22, 2020, 9:41 PM

#

what other functions can we make without using function calls?

deft pagoda May 22, 2020, 9:41 PM

#

probably all of them

#

lambdas are universal by themselves

grave jolt May 22, 2020, 9:42 PM

#

Except for map, maybe

pliant tusk May 22, 2020, 9:42 PM

#

at least all of the logical ones

inland acorn May 22, 2020, 9:42 PM

#

let's go to #esoteric-python and have a go xD

pliant tusk May 22, 2020, 9:42 PM

#

@grave jolt we already recreated map

grave jolt May 22, 2020, 9:43 PM

#

Well, it still has function calls, doesn't it?

#

Maybe vivax meant without build-in functions

rich wharf May 22, 2020, 9:50 PM

#

Suggestion: Python type annotation for loops

#

for (x: int) in [1, 2, 3]:
  ...

#

Suggestion: Python type annotation for assignment expressions