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python-3.xpython-mro

Dynamic/static analysis of method resolution order in Python


Is there a way that I can pragmatically determine, either at runtime, or via static analysis, the method resolution order for a given python class?

Imagine I have a set of classes

class A():
    ...

class B(A):
    ...

class C(A):
    ...

class D(B, C):
    def print_mro(self):
         print("D, B, C, A")

I want to find out the C3 linearization for them is without having to root through the source code and try to determine the order by hand. I'm working on a django app where the views have lots of mixins that have been up to now rather haphazardly ordered. I need to make sure that they are in the right order though, and for security reasons I don't want to check my work by hand and risk a data leak. I also don't want to go through by hand and add a print statement to every mixin's dispatch method.


Solution

  • What about

    class A():
        pass
    
    class B(A):
       pass
    
    class C(A):
        pass
    
    class D(B, C):
        def print_mro(self):
             print(self.__class__.__mro__)
    
    d = D()
    d.print_mro()
    

    ?