Python: Passing and executing class method on object

Question

I have simple class and object

class Cat():
    def pet(self):
        print('mrrrrrr')

puss = Cat()

Is there a builtin method for mechanism like this:

cat_sound = ???(puss, Cat.pet)

So I can separately pass and use object and its class function in nice way?

And I know that I can:

cat_sound = getattr(puss, 'pet')
cat_sound()

And:

 catsound = getattr(puss, Cat.pet.__name__)
 catsound()

Even this way what solves my problem but looks ugly:

 catsound = getattr(puss, getattr(Cat.pet, '__name__'))
 catsound()

EDIT: The another way is to call:

 Cat.pet(puss)

But my question is still open :)

What underlying problem are you trying to solve? If you know the method through the class, you can call it directly on the instance, so your question doesn't make yet make sense to me. — 9769953
– 9769953, Commented Feb 15, 2019 at 12:03
I wish to simply check how to pass separately object and its class method through some function and just wondering if presented in my question method exist. Anyway calling Cat.Miau(puss) do the job - but still, my question remain unanswered :D — pbaranski
– pbaranski, Commented Feb 16, 2019 at 10:42

maQ · Accepted Answer · 2019-02-19 09:13:34Z

2

There is no simpler solution than:

Cat.pet(puss)

Why does this work? Simple because self and object instance puss is the same object in the memory so when you will try to call Cat.pet() without any attribute, you will get TypeError: pet() missing 1 required positional argument: 'self' so you know what needs to be passed. Now you can create a simple function like that:

def method_executor(method_ref, obj_instance, *args, **kwargs):
    return method_ref(obj_instance, *args, **kwargs)

args and kwargs are added to maintain possibility passing values to other attributes and use it like that:

method_executor(Cat.pet, puss)

answered Feb 19, 2019 at 9:13

maQ

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Comments

Philipp F · Accepted Answer · 2019-02-15 12:05:21Z

0

I think you mean miau instead of pet in your class definition. Then you can simply do

cat_sound = puss.miau
cat_sound()

answered Feb 15, 2019 at 12:05

Philipp F

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1 Comment

pbaranski Over a year ago

Indeed - I made mistake :) Anyway - general concept is to pass separately instance and class function for future usage, and its execution :D

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