Super() in python

how-to-use-super().py

# https://stackoverflow.com/a/33469090/8379419
  
# Dependency Injection

# Other people can use your code and inject parents into the method resolution:

class SomeBaseClass(object):
    def __init__(self):
        print('SomeBaseClass.__init__(self) called')

class UnsuperChild(SomeBaseClass):
    def __init__(self):
        print('UnsuperChild.__init__(self) called')
        SomeBaseClass.__init__(self)

class SuperChild(SomeBaseClass):
    def __init__(self):
        print('SuperChild.__init__(self) called')
        super(SuperChild, self).__init__()
        
# Say you add another class to your object, and want to inject a class between Foo and Bar 
# (for testing or some other reason):

class InjectMe(SomeBaseClass):
    def __init__(self):
        print('InjectMe.__init__(self) called')
        super(InjectMe, self).__init__()

class UnsuperInjector(UnsuperChild, InjectMe): pass

class SuperInjector(SuperChild, InjectMe): pass

# Using the un-super child fails to inject the dependency because the child you're using has hard-coded 
# the method to be called after its own:

>>> o = UnsuperInjector()
UnsuperChild.__init__(self) called
SomeBaseClass.__init__(self) called

# However, the class with the child that uses super can correctly inject the dependency:

>>> o2 = SuperInjector()
SuperChild.__init__(self) called
InjectMe.__init__(self) called
SomeBaseClass.__init__(self) called