[C++-sig] overriding a C++ method

[David Abrahams]

on Wed Jul 25 2007, Francois Ostiguy <ostiguy-AT-fnal.gov> wrote:

> Hi-
>
> I need help with the following problem.
>
> Consider a c++ class
>
> class A {
>  public:
>    A();
>    .....
>    void do_something( std::vector<std::pair<double,int> >& arg);
>    ...
>  };
>
> wrapped as follows:
>
> class_< A, bases<Base>, boost::shared_ptr<A>( "A", init<>() )
> ...
> ;
>
> I want to wrap the method do_something, but I would like to avoid
> introducing a converter for std::vector<std::pair<double,int> >.
> Rather, I would like to be able to call do_something(..) in python
> using as an argument, a list of 2-tuples, which would be more natural.

void do_something(A& self, boost::python::object seq)
{
    std::vector<std::pair<double,int> > arg;
    for (
        std::size_t i = 0
      , len = boost::python::extract<std::size_t>(seq.attr("__len__"));
        i < len;
        ++i)
    {
       arg.push_back(
           std::make_pair(
               boost::python::extract<double>(seq[i][0])
             , boost::python::extract<int>(seq[i][1])
           )
       )
    }
    self.do_something(arg)
}

class_< A, bases<Base>, boost::shared_ptr<A>( "A", init<>() )
   .def("do_something", do_something)
   ...
   ;

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

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