CODEWITHSUNDEEP
python
sokokaleb
sokokaleb

Reputation: 115

Python: Static class attribute of the class itself

I recently made a class. Let's say that the class is declared as below.

class MyClass(object):
    def __init__(self, modifiers):
        ....

The problem is, I want to create constant instances of the class:

class MyClass(object):
    def __init__(self, modifiers):
        ....

    CONSTANT_MEMBER_1 = MyClass(my_modifiers)
    CONSTANT_MEMBER_2 = MyClass(my_modifiers)

Unfortunately, Python won't allow me to do so, with error:

E    NameError: global name 'MyClass' is not defined

Any solution for this problem?

One alternative would be creating a 'static' method for the class that will return a same object each time it's called (e.g., MyClass.CONSTANT_MEMBER_1()). But I think I would still prefer to access it using MyClass.CONSTANT_MEMBER_1.

Thanks.

Upvotes: 0

Views: 891

Answers (2)

wwii
wwii

Reputation: 23753

Maybe make use of inheritance and custom descriptors, Python Descriptors Demystified

class MyClass(object):
    def __init__(self, color):
        self.color = color
    def __repr__(self):
        return 'I am {}'.format(self.color)

class Foo(MyClass):
    ConstantMember_blue = MyClass('blue')
    ConstantMember_red = MyClass('red')

f = Foo('green')

>>> f
I am green
>>> f.ConstantMember_blue
I am blue
>>> f.ConstantMember_red
I am red
>>> Foo.ConstantMember_blue
I am blue
>>> Foo.ConstantMember_red
I am red
>>>

Upvotes: -1

khelwood
khelwood

Reputation: 59112

You can assign to class variables right after the class has been defined.

class MyClass(object):
    def __init__(self, modifiers):
        ....

MyClass.CONSTANT_MEMBER_1 = MyClass(my_modifiers)
MyClass.CONSTANT_MEMBER_2 = MyClass(my_modifiers)

Upvotes: 2

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