Python-从嵌套类中获取父类函数即时变量

Question

I'm having a bit of a dilemma with Python nested classes. What i'm trying to do is get variables from a function at the top level of class A and use them in the sub class B. Something like this

 class A:
   def function_A():
      value = 5

      class B:
        def function_B(self):
            print (A.value)

This method below works if i turn the variable into a class variable like below but it doesn't do what i want:

 class A:
   value = 5

      class B:
        def function_B(self):
            print (A.value)

I'm guessing that this isn't possible so can anyone provide a workaround?

Answer 1

The variable value is local to function_A , and exists only while that method is running. There is simply nothing to access when it's not executing, which will be the case when function_B is executing. In particular, in your first example it's not an attribute of A , or of any instance of A .

It's not clear from your code what you actually intend to do with such a value , so it's difficult to make further suggestions.

Answer 2

The class A has no attribute value , because the value variable is defined inside the function_A function. Therefore you don't have to access value as an attribute of the class, but as a normal variable that you can access from class B , because it is in the same scope. You have to remove the A. before value

Example:

class A:
    def function_A():
        value = 5

        class B:
            def function_B():
                print (value)

        var = B
        var.function_B()

test = A
test.function_A()