Dynamically Changing the Base Class

[Adam C.]

On Jul 7, 4:04 pm, Carl Banks <pavlovevide... at gmail.com> wrote:
> On Jul 7, 9:31 am, "Adam C." <adam... at gmail.com> wrote:
>
>
>
> > We have a situation where we want a Swig-generated Python class to
> > have a different base (not object). It doesn't appear that we can
> > coerce Swig into generating the class we want at present (but we are
> > still enquiring).
>
> > Is it possible to dynamically change the base class to something else?
> > Initial experiments appear to show it is not:
> > -------------------------------- snip -------------------------------->>> class Foo(object):
>
> >         pass
>
> > >>> class Foozle(object):
>
> >         pass
>
> > >>> Foozle.__bases__ = (Foo,)
>
> > Traceback (most recent call last):
> >   File "<pyshell#6>", line 1, in <module>
> >     Foozle.__bases__ = (Foo,)
> > TypeError: __bases__ assignment: 'Foo' deallocator differs from
> > 'object'
> > -------------------------------- snip --------------------------------
>
> > Is there a solution I am missing?
>
> > Thanks in advance.
>
> You get the same effect as subclassing by using multiple inheritance.
> Suppose your SWIG class called Foo to have a base class of Base.  You
> could instead call the SWIG class _Foo, and define Foo as a Python
> class like this:
>
> class Foo(_Foo,Base): pass
>
> If you do that, the resulting class will behave exactly as if _Foo
> were a subclass of base (apart from some introspection methods and
> edge cases).  You can see that this is so if you look at the MRO:
>
> Foo, _Foo, Base, object
>
> Which is the same MRO that would occur if _Foo derived from Base
> directly.
>
> The drawback (which is also a drawback to the hypothetical base
> reassignment) is that Foo's __init__ method won't call Base's.  The
> only way you can make SWIG __init__ call it's superclass's __init__ is
> apparently a patch.
>
> Carl Banks

Thanks. Looks like I will just write a patch step and hook it into the
makefile.