C++ Boost

(NumPy)
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binary_ufunc

A binary_ufunc is a struct used as an intermediate step to broadcast two arguments so that a C++ function can be converted to a ufunc like function

<boost/python/numpy/ufunc.hpp> contains the binary_ufunc structure definitions

synopsis

namespace boost
{
namespace python
{
namespace numpy
{

template <typename TBinaryFunctor,
          typename TArgument1=typename TBinaryFunctor::first_argument_type,
          typename TArgument2=typename TBinaryFunctor::second_argument_type,
          typename TResult=typename TBinaryFunctor::result_type>

struct binary_ufunc
{

  static object call(TBinaryFunctor & self,
                     object const & input1,
                     object const & input2,
                     object const & output);

  static object make();
};

}
}
}

constructors

struct example_binary_ufunc
{
  typedef any_valid first_argument_type;
  typedef any_valid second_argument_type;
  typedef any_valid result_type;
};
Requirements:The any_valid type must be defined using typedef as a valid C++ type in order to use the struct methods correctly
Note:The struct must be exposed as a Python class, and an instance of the class must be created to use the call method corresponding to the __call__ attribute of the Python object

accessors

template <typename TBinaryFunctor,
          typename TArgument1=typename TBinaryFunctor::first_argument_type,
          typename TArgument2=typename TBinaryFunctor::second_argument_type,
          typename TResult=typename TBinaryFunctor::result_type>
static object call(TBinaryFunctor & self,
                   object const & input,
                   object const & output);
Requires:Typenames TBinaryFunctor and optionally TArgument1 and TArgument2 for argument type and TResult for result type
Effects:Passes a Python object to the underlying C++ functor after broadcasting its arguments 
template <typename TBinaryFunctor,
          typename TArgument1=typename TBinaryFunctor::first_argument_type,
          typename TArgument2=typename TBinaryFunctor::second_argument_type,
          typename TResult=typename TBinaryFunctor::result_type>
static object make();
Requires:Typenames TBinaryFunctor and optionally TArgument1 and TArgument2 for argument type and TResult for result type
Returns:A Python function object to call the overloaded () operator in the struct (in typical usage)

Example(s)

namespace p = boost::python;
namespace np = boost::python::numpy;

struct BinarySquare
{
  typedef double first_argument_type;
  typedef double second_argument_type;
  typedef double result_type;

  double operator()(double a,double b) const { return (a*a + b*b) ; }
};

p::object ud = p::class_<BinarySquare, boost::shared_ptr<BinarySquare> >("BinarySquare").def("__call__", np::binary_ufunc<BinarySquare>::make());
p::object inst = ud();
result_array = inst.attr("__call__")(demo_array,demo_array) ;
std::cout << "Square of list with binary ufunc is " << p::extract <char const * > (p::str(result_array)) << std::endl ;
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