[C++-sig] Re: make_constructor & keyword arguments?

[David Abrahams]

"Ralf W. Grosse-Kunstleve" <rwgk at yahoo.com> writes:

> Is it possible to add keyword argument support to a constructor injected with
> boost::python::make_constructor? I tried this
>
>       .def("__init__",
>         boost::python::make_constructor(from_iselection_unsigned),
>         (arg_("size"), arg_("iselection")))
>
> but it doesn't compile ("incomplete type"). 

Full error message please?

> I also tried using operator() and
> operator[] of the make_constructor instance; it compiles but doesn't work at
> runtime. 

Not surprising.  make_constructor just returns a callable
python::object, so operator() and operator[] just do the ordinary
things you might expect to that object.

> What is the correct syntax?

I think you need a "self" argument, though I might be wrong.

       .def("__init__",
            boost::python::make_constructor(
                from_iselection_unsigned
                , (arg_("self"), arg_("size"), arg_("iselection"))
            ))

The reference docs for make_function/make_constructor need to be
fixed, as I posted last week.

-- 
Dave Abrahams
Boost Consulting
http://www.boost-consulting.com