How to call a data member of the base class if it is being overwritten as a property in the derived class?
descriptor, inheritance, overloading, python
Solution
Defining
def __init__(self):
self.foo = 5
in `Base` makes `foo` a member (attribute) of the instance, not of the class. The class `Base` has no knowledge of `foo`, so there is no way to access it by something like a `super()` call.
This is not necessary, however. When you instanciate
foobar = Derived()
and the `__init__()` method of the base class calls
self.foo = 5
this will not result in the creation / overwriting of the attribute, but instead in `Derived`'s setter being called, meaning
self.foo.fset(5)
and thus `self._foo = 5`. So if you put
return 1 + self._foo
in your getter, you pretty much get what you want. If you need the value that `self.foo` is set to in `Base`'s constructor, just look at `_foo`, which was set correctly by the `@foo.setter`.
Problem
This question is similar to this other one, with the difference that the data member in the base class is not wrapped by the descriptor protocol. In other words, how can I access a member of the base class if I am overriding its name with a property in the derived class? ``` class Base(object): def __init__(self): self.foo = 5 class Derived(Base): def __init__(self): Base.__init__(self) @property def foo(self): return 1 + self.foo # doesn't work of course! @foo.setter def foo(self, f): self._foo = f bar = Base() print bar.foo foobar = Derived() print foobar.foo ``` Please note that I also need to define a setter because otherwise the assignment of self.foo in the base class doesn't work. All in all the descriptor protocol doesn't seem to interact well with inheritance...