is there a way to check if a param contains a class or a class instance?

Question

I want the wrapper my_function to be able to receive either a class or class instance, instead of writing two different functions:

>>> from module import MyClass

>>> my_function(MyClass)

True

>>> cls_inst = MyClass()

>>> my_function(cls_inst)

True

the problem is that I don't know in advance which type of classes or class instances I am going to receive. So I can't, for example, use functions like isinstance...

How can I type check if a param contains a class or a class instance, in a generic way?

Any idea?

Could you provide a use case for doing this? It doesn't make a lot of sense on the surface. Why can't you use my_function( object.__class__ ) so that things are at least consistent? — S.Lott
– S.Lott, Commented Oct 28, 2009 at 17:54

SilentGhost · Accepted Answer · 2009-10-28 17:11:06Z

7

>>> class A: pass

>>> isinstance(A, type)
True
>>> isinstance(A(), type)
False

answered Oct 28, 2009 at 17:11

SilentGhost

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1 Comment

steveha Over a year ago

Your example is an old-style class, but this does also work with new-style classes.

Jonathan Feinberg · Accepted Answer · 2009-10-28 17:14:10Z

1

import types

def myfun(maybe_class):
    if type(maybe_class) == types.ClassType:
        print "It's a class."
    else:
        print "It's an instance."

answered Oct 28, 2009 at 17:14

Jonathan Feinberg

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Comments

jldupont · Accepted Answer · 2009-10-28 17:10:54Z

0

Use the type() buitlin function.

E.g.:

import avahi
print type(avahi)

<type 'module'>

answered Oct 28, 2009 at 17:10

jldupont

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