[C++-sig] Re: iterators and abstact base class

[Francois Ostiguy]

On Wed, 10 Mar 2004, David Abrahams wrote:

> > I want to achieve in python
> >
> > b1 = B(..)    # appropriate contructor
> > b2 = B(..)    #
> > c = C(b1, b2) # constructs a C which contains b1 and b2
> > i = I(c)      # i is an iterator for c
> >
> > a = i.next()  <<<<==== this is the problem. i.next() must return something
> >                        that can be held into python object a. In C++
> >                        i.next() returns a type A*.
> >
> > a.function()
> >
> > ...
> >
> > How do I define a python type that can be used to hold what i.next() returns ?
>
> I don't understand the problem.  Why not wrap "A" using class_; then
> wrap next() with reference_existing_object or another appropriate call
> policy?
>

I am affraid the problem is sitting in front of my keyboard.
I guess I did not fully appreciate the fact that introspection allows
one to determine the dynamic type of an object and to return a reference
to the full type intead of a reference to a base class object.
Thanks again!



-Francois

----------------------------------------------------------------------------
Dr. Jean-Francois OSTIGUY                              voice: (630) 840-2231
Beam Physics Dept MS220                                  FAX: (630) 840-6039
Fermi National Accelerator Laboratory                email: ostiguy at fnal.gov
Batavia IL 60510-0500                           WWW:www-ap.fnal.gov/~ostiguy