Re: [pygccxml-development] Default template parameters

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

On Wed, Feb 17, 2010 at 1:49 PM, Berserker <ber...@ho...> wrote:
> Hi, I found a problem in the wrapper code generated by Py++ on functions
> with default template parameters (with more than one template parameter)
> Example:
>
> class Foo
> {
> public:
>    void test( const std::map<std::string, std::string> & p =
>    std::map<std::string, std::string>() );
> };
>
> Py++ actually generates:
>
> struct Foo_wrapper : public ...
> {
>
> static void test( ::Foo & inst, std::map< std::string, std::string > const &
> p = std::map<std::basic_string<char, std::char_traits<char>,
> std::allocator<char> >, std::basic_string<char, std::char_traits<char>,
> std::allocator<char> > >() )
> {
> // My pre_call_code
>
> inst.test(p);
>
> // My post_call_code
> }
>
> }
>
> and
>
> typedef void ( *test_function_type )( ::Foo &,std::map<std::string,
> std::string> const & );
>
> Foo_exposer.def(
> "test"
> , test_function_type( &Foo_wrapper::test )
> , ( ::boost::python::arg("inst"),
> ::boost::python::arg("p")=std::map<std::basic_string<char,
> std::char_traits<char>, std::allocator<char> >, std::basic_string<char,
> std::char_traits<char>, std::allocator<char> > >() ) );
>
> On VC8 this code compiles fine, but on GCC ( due to a bug reported here
> http://stackoverflow.com/questions/851584/default-template-class-argument-confuses-g
> )
> it doesn't. On the last GCC version this problem seems fixed but on GCC 4.2
> (tested on MAC)
> I can reproduce it.
>
> Is there a quick fix to "protect" default arguments with ( )? An alternative
> solution would
> be to define an "alias" for the template, something like this:
>
> struct Foo_wrapper : public ...
> {
>
> static void test( ::Foo & inst, std_map_string_string const & p=
> std_map_string_string() )
> {
> // My pre_call_code
> inst.test(p);
> // My post_call_code
> }
>
> }
>
> and
>
> typedef void ( *test_function_type )( ::Foo &,std_map_string_string const &
> );
>
> Foo_exposer.def(
> "test"
> , test_function_type( &Foo_wrapper::test )
> , ( ::boost::python::arg("inst"),
> ::boost::python::arg("p")=std_map_string_string() ) );
>
>
> is it already possible?

Yes. I suggest you to read the following document:
http://language-binding.net/pygccxml/upgrade_issues.html

The bottom line  - change argument default value:

mb.calldef( 'test' ).arguments[0].default_value = mb.calldef( 'test'
).arguments[0].default_value + '()'

HTH

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