[Boost-users] [python] howto expose iterator / range with parameter?

From: Jörg Becker (news_at_[hidden])
Date: 2008-04-09 12:15:17

Hello,

I want to expose a begin and end method which takes one argument and returns 
an iterator as a python iterator. Here is an example:

struct range_test {
  typedef std::list< int > my_type;
  typedef my_type::iterator iterator;
  my_type m_vals;

  my_type::iterator begin ( int i ) { return m_vals.begin(); }
  my_type::iterator end ( int i ) { return m_vals.end();}
};

class_< range_test >( "range_test" )
  .def( "get_iter", range( &range_test::begin, &range_test::end ) )
  ;

If I import this, python exists immediately without any error message. Trying 
it with wrappers, I get a (gcc) compile error saying my wrapper function is 
not a class, struct, or union type:

range_test::iterator begin( range_test & t, int i ) { return t.begin( i ); }
range_test::iterator end( range_test & t, int i ) { return t.end( i ); }
class_< range_test >( "range_test" )
  .def( "get_iter", range( &range_test::begin, &range_test::end ) )
  .def( "iter_wrapper", range( begin, end ) )
  ;

So I'm wondering how to expose such iterators, e.g. a method taking a 
predicate and returning a filter_iterator.

Thanks for any help

Jörg