调用同一基类中定义的另一个方法的基类的方法可能最终调用覆盖它的派生类的方法

Question

I am reading python documentaitin at: https://docs.python.org/3/tutorial/classes.html

I am having trouble understanding the following:

Because methods have no special privileges when calling other methods of the same object, a method of a base class that calls another method defined in the same base class may end up calling a method of a derived class that overrides it. (For C++ programmers: all methods in Python are effectively virtual.)

Say base class X has method A that calls method B in the same base class.

Now a derived class Y, say has method B, and user invokes YA(). Then, method A from Class X will be invoked and it will call method B from Class Y? Is this what author is trying to say?

Answer 1

I assume this it what he means

In [8]: class A:
   ...:     def foo(self):
   ...:         print ('foo')
   ...:         self.bar()
   ...:     def bar(self):
   ...:         print ('bar')
   ...:

In [9]: class B(A):
   ...:     def bar(self):
   ...:         print('bar but in b')
   ...:

In [10]: obj = B()

In [11]: obj.foo()
foo
bar but in b

In line 11, obj.foo() calls foo in class B, since its non existent, it goes to foo in class A, which then calls bar , since B has bar it calls it instead of bar in class A

If you have access to a debugger like pycharm it would be easier to follow it step by step