I need an expert's help with the Python type system. Can I do something like:
class I(object): pass
class A(I): pass
class B(I): pass
my_parents = [A, B]
class C(*my_parents): pass
Basically I want to determine the inheritance chain at runtime, avoiding any potential issues resulting from the diamond problem. What's the best way to do something like that?
You can define classes dynamically using the 3-argument form of type:
C = type('C', tuple(my_parents), {})
class I(object): pass
class A(I): pass
class B(I): pass
my_parents = [A, B]
# class C(*my_parents): pass # works in Python3 but not in Python2
C = type('C', tuple(my_parents), {})
print(C.__bases__)
yields
(<class '__main__.A'>, <class '__main__.B'>)
Note: I don't know what you mean by "avoiding any potential issues resulting from the diamond problem". You will have an inheritance diamond if you use A and B as bases of C. If the issue you are referring to is how to call parent methods, the solution of course is to use super.
