Nice solution wanted: Hide internal interfaces

[alex23]

On Oct 30, 2:33 am, Johannes Bauer <dfnsonfsdu... at gmx.de> wrote:
> I'm currently looking for a good solution to the following problem: I
> have two classes A and B, which interact with each other and which
> interact with the user. Instances of B are always created by A.
>
> Now I want A to call some private methods of B and vice versa (i.e. what
> C++ "friends" are), but I want to make it hard for the user to call
> these private methods.

One approach could be to only have the public interface on B, and then
create a wrapper for B that provides the private interface:

    class B:
        def public_method(self):
            pass

    class B_Private:
        def __init__(self, context):
            self.context = context

        def private_method(self):
            # manipulate self.context

    class A:
        def __init__(self):
            self.b = B()
            self.b_private = B_Private(self.b)

        def foo(self):
            # call public method
            self.b.public_method()

            # call private method
            self.b_private.private_method()

It doesn't stop a user from accessing the private methods, but it does
separate them so they have to *intentionally* choose to use them.