[C++-sig] Re: Problem With Calling Methods on Python Subclasses from C++

David Abrahams dave at boost-consulting.com
Sun Oct 17 17:33:07 CEST 2004

Mark Rowe <lists.python.org at bdash.net.nz> writes:

> class _ErrorHandlerWrapper : public ErrorHandler, public wrapper<ErrorHandler>
> {
>     public:
>         virtual void handleError(const Error & err) const {
>             if (override f = this->get_override("handleError"))
>             {
>                 f(err);

If you want the type of err to be preserved, you have to pass it by


>             }
>             else
>                 ErrorHandler::handleError(err);
>         }
> };

Boost.Python never passes anything by reference, by default, because
it's unsafe: it can lead to dangling pointers.  It would be very
interesting to consider copying and passing whole most-derived class
instances by value, but that's not implemented.

Dave Abrahams
Boost Consulting

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