[C++-sig] Another bug in pyplusplus

[Niall Douglas]

If you disable use of keywords using 
mb.calldefs().use_keywords=False, pyplusplus also stops inserting 
default argument values into its wrappers eg;

int FXDialogBox::execute(int placement=DEFAULT)

... should become

    virtual ::FX::FXuint execute( ::FX::FXuint placement = 
FX::DEFAULT ) {
        if( bp::override func_execute = this->get_override( "execute" 
) )
            return func_execute( placement );
        else
            return FX::FXDialogBox::execute( placement );
    }

Unfortunately, it's missing the default argument. To fix this, 
replace calldef_wrapper_t.args_declaration() with:

    def args_declaration( self ):
        args = []
        boost_obj = algorithm.create_identifier( self, 
'::boost::python::object' )
        for index, arg in enumerate( self.declaration.arguments ):
            result = arg.type.decl_string + ' ' + 
self.argument_name(index)
            if arg.default_value:
                if not declarations.is_pointer( arg.type ) or 
arg.default_value != '0':
                    result += '=%s' % arg.default_value
                else:
                    result += '=%s()' % boost_obj
            args.append( result )
        if len( args ) == 1:
            return args[ 0 ] 
        return ', '.join( args )

Another point - I believe the default_X function doesn't need to be 
virtual. By making it so, you're introducing an unnecessary 
inefficiency:    
    
    virtual ::FX::FXuint default_execute( ::FX::FXuint placement ) {
        return FX::FXDialogBox::execute( placement );
    }

Cheers,
Niall