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Subject: Difference method vs attribut = function
From: Ulrich Goebel
Newsgroups: comp.lang.python
Date: Fri, 28 Jun 2024 16:08 UTC
References: 1

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From: ml@fam-goebel.de (Ulrich Goebel)
Newsgroups: comp.lang.python
Subject: Difference method vs attribut = function
Date: Fri, 28 Jun 2024 18:08:54 +0200
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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>

Subject: Re: Difference method vs attribut = function
From: Stefan Ram
Newsgroups: comp.lang.python
Organization: Stefan Ram
Date: Sat, 29 Jun 2024 20:48 UTC
References: 1

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From: ram@zedat.fu-berlin.de (Stefan Ram)
Newsgroups: comp.lang.python
Subject: Re: Difference method vs attribut = function
Date: 29 Jun 2024 20:48:58 GMT
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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:

Main.py

class c:
def m():
pass

print( *( name for name in dir( c )if not name.startswith( '__' )))

sys.stdout

>class MyClass:
> def __init__(self):
> functionAttribute = None

Your local name "functionAttribute" is not an attribute of "MyClass".
>mc = MyClass()
>mc.functionAttribute = function

Above, you only add an attribute to "mc", not to "MyClass".

>By the way: in my usecase I want to pass different functions
>to different instances of MyClass.

class MyClass:
def __init__( self ):
self.function = None
def accept( self, function ):
self.function = function

mc = MyClass()
mc.accept( print )

mc_1 = MyClass()
mc_1.accept( dir )

Subject: Re: Difference method vs attribute = function (Posting On Python-List Prohibited)
From: Lawrence D'Oliv
Newsgroups: comp.lang.python
Organization: A noiseless patient Spider
Date: Sat, 29 Jun 2024 22:55 UTC
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From: ldo@nz.invalid (Lawrence D'Oliveiro)
Newsgroups: comp.lang.python
Subject: Re: Difference method vs attribute = function (Posting On Python-List
Prohibited)
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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.

Subject	Author
Difference method vs attribut = function	Ulrich Goebel
Re: Difference method vs attribut = function	Stefan Ram
Re: Difference method vs attribute = function (Posting On Python-List Prohibited	Lawrence D'Oliveiro