How ambiguity is removed in python as it support multiple inheritance?

Question

If I write same method in two class how interpreter decides which one to execute.

class A:
   method1():
      pass
class B:
  method1():

class C(A,B):

The class C is inherites both class A and B How do I call Method1() of B class.

Please clarify. The title of this post asks one question but the question inside the post asks something slightly different. By asking the second question you seem to know that the MRO says that instances of class C will have their `method1` call A's version. So do you know that for certain and just want help accessing the B version of the method? (Also you forgot the `self` parameters BTW.) — Ray Toal, Mar 12 '18 at 06:57
Duplicate question its already answered at https://stackoverflow.com/questions/3810410/python-multiple-inheritance-from-different-paths-with-same-method-name — Sateesh Telaprolu, Mar 12 '18 at 06:58
It's my mistake but still I wan't to call class b method1() how do i call it — Vikas Satpute, Mar 12 '18 at 07:45
If you are want to call Method1() from B class, just change the order of inheritance in class C like this `class C(B,A):` @VikasSatpute — Debashis, Oct 16 '21 at 06:02

score 2 · Accepted Answer · answered Mar 12 '18 at 06:59

2

It takes the first instance

class A:
    def method(self):
        print ("a")
class B:
    def method(self):
        print ("b")

class C(A,B):
    pass

result

>>> a = C()
>>> a.method()
a

answered Mar 12 '18 at 06:59

Samuel Muiruri

How to call the method() of Class B? – Vikas Satpute Mar 12 '18 at 07:28
you're implementation method is bad practice in python maybe different way is A inherits B then B inherits C so you have a tree – Samuel Muiruri Mar 12 '18 at 07:30
or name the functions differently – Samuel Muiruri Mar 12 '18 at 07:30
The code that you have written is correct but if I wan't to use function method() of class B then how do I call it from outside – Vikas Satpute Mar 12 '18 at 07:42

score 1 · Answer 2 · edited Oct 16 '21 at 09:43

If we see the Method Resolution Order(MRO) for class C, we see the following:

[<class '__main__.C'>, <class '__main__.A'>, <class '__main__.B'>, <class 'object'>].

Since A is mentioned first during the statement class C(A,B):, the preference for A is higher than B when there is an ambiguity.

To simply call the method1 from class B, we need to reverse the order mentioned in the class C declaration to this: class C(B,A):

Now the MRO is changed to if we are checking like this - C.mro()

[<class '__main__.C'>, <class '__main__.B'>, <class '__main__.A'>, <class 'object'>]

2 Answers2