[C++-sig] Re: Re: abstract base class

Mike Rovner mike at bindkey.com
Sat Nov 23 00:47:26 CET 2002


"David Abrahams" <dave at boost-consulting.com> wrote in message
news:ulm3lfbhl.fsf at boost-consulting.com...
> >> You should try :
> >>
> >>     class_<LayerOperation, boost::noncopyable>("Operation", no_init);
> >>
> >  (a) why that happened?
>
> Because if you don't tell it that LayerOperation is noncopyable,
> Boost.Python tries to register a converter for handling wrapped
> functions which handle function return values of type
> LayerOperation. Naturally, this has to be able to copy construct the
> returned LayerOperation object into storage that can be managed by a
> Python object. Since your LayerOperation is an abstract class, that
> fails.

Thank you. Now it's clear. I've added that to moin.moin.

> >  (b) error message is inadequate.
>
> I guess that's not a question. Well, I'm truly sorry, but the control
> we poor C++ library writers get over the error messages emitted by
> your C++ compiler is limited at best.

:)








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