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Difference method vs attribut = function

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  Difference method vs attribut = function Ulrich Goebel <ml@fam-goebel.de> - 2024-06-28 18:08 +0200
    Re: Difference method vs attribute = function (Posting On Python-List Prohibited) Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-06-29 22:55 +0000

#196346 — Difference method vs attribut = function

Hi,

a class can have methods, and it can have attributes, which can hold a function. Both is well known, of course.

My question: Is there any difference?

The code snipped shows that both do what they should do. But __dict__ includes just the method, while dir detects the method and the attribute holding a function. My be that is the only difference?


class MyClass:
    def __init__(self):
        functionAttribute = None
        
    def method(self):
        print("I'm a method")

def function():
    print("I'm a function passed to an attribute")

mc = MyClass()
mc.functionAttribute = function

mc.method()
mc.functionAttribute()

print('Dict: ', mc.__dict__)    # shows functionAttribute but not method
print('Dir:  ', dir(mc))        # shows both functionAttribute and method


By the way: in my usecase I want to pass different functions to different instances of MyClass. It is in the context of a database app where I build Getters for database data and pass one Getter per instance.

Thanks for hints
Ulrich


-- 
Ulrich Goebel <ml@fam-goebel.de>

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#196351 — Re: Difference method vs attribute = function (Posting On Python-List Prohibited)

On 29 Jun 2024 20:48:58 GMT, Stefan Ram wrote:

> Ulrich Goebel <ml@fam-goebel.de> wrote or quoted:
>>a class can have methods, and it can have attributes, which can hold a
>>function. Both is well known, of course.
> 
>   Methods are attributes too:

They are indeed:

    class A:
        def set_x(self, x) :
            self.x = x
        #end set_x
    #end A

    class B:
        pass
    #end class B

    def set_x(self, x) :
        self.x = x
    #end set_x

    B.set_x = set_x

    AInst = A()
    AInst.set_x(9)
    print(AInst.x)
    BInst = B()
    BInst.set_x(4)
    print(BInst.x)

Output:

    9
    4

No fundamental difference between the two ways of attaching a method to a 
class.

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