从类方法函数调用变量到普通方法

Question

I would like to call a variable from a classmethod to a different method inside the same class:

class A():
    @classmethod
    def b(cls):
        cls.g = 5
    def c(self):
        if self.g < 1:
            print("TestA")
        else:
            print("TestB")

When doing:

x = A()
x.c()

I get:

AttributeError: 'A' object has no attribute 'g'

I've read and searched for a similar case but haven't found one. Most deal with calling variables from the init method and that doesn't apply here.

Answer 1

If you don't run .b() beforehand, your .g doesn't exist,...at all.

Add an __init__ function to your class and declare .g there to make sure it exists at least.

Answer 2

You did not define g as a class attribute of the class A . This could be done this way:

class A():
    g = 7

but then in your code you are treating g as instance ( self.g ) and class variable ( cls.g ) at the same time. While this works ( self.g will refer to cls.g ) it may be confusing.