Re: Difference method vs attribut = function
Ulrich Goebel wrote at 2024-6-28 18:08 +0200: >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? I think you should make the distinction "class versus instance attribute" rather than "mether versus function". If you look at the `__dict__` of an instance, you see only the instance variables (the class's `__dict__` gives you the (most) attributes of the class). You can access (most) class attributes via an instance; if a function is accessed in this way, it becomes (typically) a method. -- https://mail.python.org/mailman/listinfo/python-list
Re: Difference method vs attribut = function
On 6/28/2024 12:08 PM, Ulrich Goebel via Python-list wrote:
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
https://docs.python.org/3/library/functions.html#dir -
object.__dict__¶
A dictionary or other mapping object used to store an object’s
(writable) attributes.
dir(object)
...
With an argument, attempt to return a list of valid attributes for that
object.
"functionAttribute" is a class method, not an instance method. If you
want an instance method:
class MyClass:
def __init__(self):
functionAttribute = None
self.instance_functionAttribute = None
def method(self):
print("I'm a method")
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Re: Difference method vs attribut = function
On 6/28/24 10:08, Ulrich Goebel via Python-list wrote: 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. If I understood what you're trying to accomplish, you could take a look here (possibly a bit complex for what you need). https://refactoring.guru/design-patterns/strategy/python/example -- https://mail.python.org/mailman/listinfo/python-list
Re: Difference method vs attribut = function
On 2024-06-28 18:08:54 +0200, Ulrich Goebel via Python-list wrote:
> 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,
The other way around: It includes only the attributes, not the methods.
> 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")
Here is the other main difference: The object is not passed implicitely
to the function. You have no way to access mc here.
You can create a method on the fly with types.MethodType:
import types
mc.functionAttribute = types.MethodType(function, mc)
> 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.
Or in this case, since each function is specific to one instance, you
could just use a closure to capture the object. But that might be
confusing to any future maintainers (e.g. yourself in 6 months), if the
method doesn't actually behave like a method.
hp
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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
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Ulrich Goebel
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