Today let's find out what is the purpose of the callable function and in which versions of python it does not work.

S0-E28/E30 :)

Callable

A callable is a function that checks other methods/functions/classes to find out if that particular element has a __call__ implemented.

Since variables like int or boolean will not have that, making :

callable(1)

or

callable(True)

Will output a "False". Meaning that those elements are not callable.

But let's check if an object will return true.

class ASimpleClass():
    pass

element1 = ASimpleClass()
callable(element1)

No. It does not - why? because it's an Object, not a Callable.

Now Let's find out if a class will be a callable:

class Test():
    pass
callable(Test)

And sure thing, it does.

Also for functions it is valid:

def function1():
    pass
assert callable(function)
assert not callable(function())

Is there a situation where you would not recommand callable?

Yes. In fact, callable was removed between 3.0 to 3.2. In 3.2 + it was brought back.

So I would check if we are using 3.0 to 3.2 python. If yes, then I would not use callable. I would then check with code like that:

isinstance(f, collections.Callable)

Acknowledgement

• What is a callable in python
• Callable at 3.6.4 python docs
• Python callable()
• What's new in Python 3.0 - Python 3.1.5 documentation

Thanks!

That's it :) Comment, share or don't :)

If you have any suggestions what I should blog about in the next articles - please give me a hint :)

See you tomorrow! Cheers!