🔒 Returning bool by checking a type

[latent forge]

Currently my code checks if a class type corresponds to the correct class by changing it to a string and checking that the type returned as a string corresponds to the string that ive been given like the photo attached. Is there another way I can do this

[supple turret]

@latent forge

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[bitter cliff]

!d isinstance

[supple turret]

isinstance

isinstance(object, classinfo)```
Return `True` if the *object* argument is an instance of the *classinfo* argument, or of a (direct, indirect, or [virtual](https://docs.python.org/3/glossary.html#term-abstract-base-class)) subclass thereof. If *object* is not an object of the given type, the function always returns `False`. If *classinfo* is a tuple of type objects (or recursively, other such tuples) or a [Union Type](https://docs.python.org/3/library/stdtypes.html#types-union) of multiple types, return `True` if *object* is an instance of any of the types. If *classinfo* is not a type or tuple of types and such tuples, a [`TypeError`](https://docs.python.org/3/library/exceptions.html#TypeError) exception is raised. [`TypeError`](https://docs.python.org/3/library/exceptions.html#TypeError) may not be raised for an invalid type if an earlier check succeeds.

Changed in version 3.10: *classinfo* can be a [Union Type](https://docs.python.org/3/library/stdtypes.html#types-union).

Similar names: 2to3fixer.isinstance

[bitter cliff]

this?

[vital agate]

instead of str you may want repr() but isistance should be better to use

[hardy ferry]

return type(self.store) is RouteSeries

[hardy ferry]

this checks exact class. it doesn't check for subclasses

to also include subclasses use isinstanceof()

[latent forge]

ty

[coral badger]

That should have been isinstance()

[trim heath]

It will not work if you import the same class from different modules
What I do

def is_subclass(cls, class_name):
    return class_name.__name__ in {c.__name__ for c in cls.mro()}

[willow lily]

== also suffice

[willow lily]

then are they really the same though ?

checking for class name seems like a very bad practice

[trim heath]

Sorry, my bad. I meant the same class from the same module, in different ways

Like, absolute vs relative import

The "module" part of the class will be different, and the classes are not equal

Even though you import from the same place

[willow lily]

then a solution based on inspect.getsource would be way more reliable imo

but that's like killing a fly with a tank

[trim heath]

An OSError is raised if the source code cannot be retrieved. A TypeError is raised if the object is a built-in module, class, or function.

I'll just check the name :)

Seems like a pythonic solution to me

[willow lily]

heh, if you have 2 very different classes having the same name from 2 different packages this method could return True though

which is way more plausible to happen than the same class from the same package being imported twice differently

[trim heath]

I encountered the second problem and reached for checking the name

[willow lily]

it wouldn't be built-in so it would work

anyway, in the absolute majority of usecases, checking type is enough

[trim heath]

I needed to check if an error is a subclass of some type (I use custom types RetryableError and NonRetryableError as mixins), and only this worked

[willow lily]

that's very specific to you though

[trim heath]

Not saying it isnt

[willow lily]

the better method would be to have a ref storage in the class that stores a reference to all the objects created from it and then check identity on those

[trim heath]

I'll do that if this bites me

Doesn't seem likely so far

[supple turret]

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