[bccdee]

That's not true. If Outer has a member Inner, Outer always has to invoke `my_inner.foo()` to use Inner::foo, and `foo()` always refers to Outer::foo (and some languages will force you to write `self.foo()`, which is even better).

If Outer extends Inner, though, you can't tell whether `foo()` refers to Inner::foo or Outer::foo without checking to see whether Outer overrides foo or not. And the number of places you have to check scales linearly with the depth of the inheritance hierarchy.