[C++-sig] same to_python_converter in multiple modules?

[Ralf W. Grosse-Kunstleve]

--- David Abrahams <david.abrahams at rcn.com> wrote:
> These are all good questions. Right now, I think the behavior is to assert
> if you supply two to_python converters for the same type. Since conversions
> go into a global registry and since there are no criteria upon which to
> choose a to_python conversion other than the source type, it is treated as
> an error to register two converters for the same type. What would the
> most-useful behavior be? You can of course avoid multiple registrations by
> creating a common shared library (or Python module if need be) which
> registers the converter and sets a global variable to prevent multiple
> registration.

Common shared library sounds OK, but the global variable is redundant. How
about enriching the Boost.Python interface:

  boost::python::to_python_converter<
    boost::array<int, 3>, bpl::boost_array_to_tuple<int, 3> >(
      boost::python::do_nothing_if_already_registered());

If the alternative as an assert, even that is redundant, but makes it clear
what will happen and it leaves the door open for future more sophisticated
mechanisms.

Ralf


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