🔒 Difference between f=int and def g(x): return int(x)?

[mighty marlin]

How is f different from g? Exactly, Demo.f works but Demo.g does not. I am pretty sure both get the self parameter, but what happens to it in the f case? (I have more tests but they show the same result.)

f = int
def g(x):
    return int(x)

class Demo():
    def this_works(self, n):
        return int(n)

    def not_this(self, m):
        return int(self, m)

Demo.this_also = Demo.this_works
Demo.surprisingly = int

Demo.f = f
Demo.g = g

d = Demo()

n=0
for af in [d.this_works, d.this_also, d.not_this, d.f, d.g]:
    n += 1
    print(f'Test #{n} of {str(af)}')
    try:
        print(af(str(n)))
    except TypeError as e:
        print(f'Failed with {e}')

[thin hatch]

@mighty marlin

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[tidal prairie]

int is a callable class/type
g is a function

lemme test it myself

int is a class. so when you assign it to demo type. it is set as an attribute, like a typeObject

g is a function. so when you assign it to demo type. it is set as an method and methods take an instance of self. which your function does not. hence it throws the error

[coarse needle]

g behaves as expected. doing Demo.g = g is basically the same as defining g in your class.

[mighty marlin]

that sounds like part of it... so what happens to the self parameter in f? does the callable class not get it?

[tidal prairie]

noop, it doesn't, since its a class (?) (citation needed)

[coarse needle]

int is a type.. meaning it got an __init__ and that one has a self defined

[tidal prairie]

oh, so you are essentially initializing Demo class as an int

[mighty marlin]

in case it wasn't clear - I saw this code as part of the Lark parser and did not understand why int worked when it looked different from my this_works function

[coarse needle]

!e

class myint:
    def __init__(self, val):
        self.val = val

class Demo:
    ...

Demo.f = myint

d = Demo()
d.f(123)

[thin hatch]

@coarse needle :warning: Your 3.12 eval job has completed with return code 0.

[No output]

[coarse needle]

int works for the same reason myint works, I'd assume.

it's a class/type.. not a function

it's not getting converted to a bound method

[mighty marlin]

ah, thanks. now i also understand a man's comment above

!close

[thin hatch]

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