From: Gennady <gfb@...>
Date: 2003-03-11T01:26:58+09:00
Subject: Re: Limited Support for Multiple Inheritance in SWIG/Ruby

How about this:

For every C++ class (Base1, Base2, Base3) we create a pair of Ruby objects:

module Base1_internals
  # Here come all instance methods of Base1
end

class Base1
  include Base1_internals
  # Other Base1 stuff
end

# Same for Base2
# Same for Base3

Then for Derrived we may have:

module Derrived_internals
  # Here come all instance methods of Derrived
end

class Derrived
  include Derrived_internals
  include Base1_internals
  include Base2_internals
  include Base3_internals
  # Other Derrived stuff
end

Hope this helps,
Gennady.

----- Original Message -----
From: <lyle@knology.net>
To: "ruby-talk ML" <ruby-talk@ruby-lang.org>; <swig-dev@cs.uchicago.edu>
Cc: <ruby-talk@ruby-lang.org>
Sent: Monday, March 10, 2003 7:41 AM
Subject: Limited Support for Multiple Inheritance in SWIG/Ruby


> All,
>
> We'd like to be able to provide support for a kind of "limited" multiple
> inheritance in SWIG's Ruby module. It is limited in the sense that, since
> Ruby doesn't support MI, we'll obviously never have the case that class
"D"
> is a direct subclass of more than one base class. However, it might be
> useful to provide support for this kind of C++ class structure:
>
>     class Base1 {
>     public:
>         void base1();
>     };
>
>     class Base2 {
>     public:
>         void base2();
>     };
>
>     class Base3 {
>     public:
>         void base3();
>     };
>
>     class Derived : public Base1, public Base2, public Base3 {
>     public:
>     };
>
> With the limited MI I'm thinking about, all three C++ classes would get
> wrapped by SWIG as Ruby classes, with "Derived" being a subclass of
"Base1"
> only. The bonus, however, would be that you'd also be able to call any of
> the methods declared for "Base2" or "Base3" (and their ancestors) on an
> instance of "Derived".
>
> The simplest solution so far seems to be to override Derived's
> #method_missing method, something like this (pseudocode):
>
>     class Derived
>       def method_missing(mth, *args)
>         for each base other than Base1
>           see if this base can handle it
>         end
>         super # call Object#method_missing
>       end
>     end
>
> but I haven't tried to implement this yet.
>
> Can someone else point out the flaws in this, and/or suggest other
> possibilities?
>
> Thanks in advance,
>
> Lyle
>
>