Re: [pygccxml-development] help with constructor default argument error

[Roman Y. <rom...@gm...>]

On Tue, Feb 26, 2008 at 2:11 AM, Kevin Watters <kev...@gm...> wrote:
> I'm new to Py++ but I've been experimenting with wrapping wxWidgets,
>  the cross platform GUI library.

Let me know if you need help with this.

>  It has gone fairly well, but I'm getting the following error and I'm
>  not sure how to resolve it.
>
>  In a header file somewhere, a global called "wxPanelNameStr" is declared:
>
>     extern WXDLLEXPORT_DATA(const char) wxPanelNameStr[];
>
>  The implementation is in a CPP file somewhere else:
>
>     extern WXDLLEXPORT_DATA(const char) wxPanelNameStr[] = "panel";
>
>  My problem arises in a constructor which uses wxPanelNameStr as the
>  default value for one of its arguments:
>
>     inline wxWindow(wxWindow *parent, wxWindowID winid,
>             const wxPoint& pos = wxDefaultPosition,
>             const wxSize& size = wxDefaultSize,
>             long style = 0,
>             const wxString& name = wxPanelNameStr)
>
>  Py++ generates the following code for this:
>
>         .def( bp::init< wxWindow *, wxWindowID, bp::optional< wxPoint
>  const &, wxSize const &, long int, wxString const & > >((
>  bp::arg("parent"), bp::arg("winid"), bp::arg("pos")=wxDefaultPosition,
>  bp::arg("size")=wxDefaultSize, bp::arg("style")=(long int)(0),
>  bp::arg("name")=wxPanelNameStr )) );
>
>  You'll note that the sixth argument takes a value of type const
>  wxString&, but the default argument in the generated code is const
>  char []. The error I get is long and does lots of complaining about
>  convertables and char[], but ultimately I think it boils down to this
>  line:
>
>  ../boost_1_34_1/boost/python/type_id.hpp:88: error: invalid use of
>  array with unspecified bounds
>
>  wxString does have a constructor which takes const char*, so the
>  implicit conversion should happen, but I think Boost::Python is
>  getting confused.
>
>  Does anyone know how I can resolve this?

mb = module_builder_t( ... )
#find wxWindow constructor with 6 arguments of any type
wxWindow = mb.constructor( 'wxWindow', arg_types=[None]*6 )
wxWindow.arguments[-1].default_value = 'wxString( wxPanelNameStr )'

This should be enough.

I also will check whether Py++ can generate better code in this use-case.

-- 
Roman Yakovenko
C++ Python language binding
http://www.language-binding.net/