Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. — Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

C++ Boost

(NumPy)
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unary_ufunc

A unary_ufunc is a struct used as an intermediate step to broadcast a single argument so that a C++ function can be converted to a ufunc like function

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

synopsis

namespace boost
{
namespace python
{
namespace numpy
{

template <typename TUnaryFunctor,
          typename TArgument=typename TUnaryFunctor::argument_type,
          typename TResult=typename TUnaryFunctor::result_type>
struct unary_ufunc
{

  static object call(TUnaryFunctor & self,
                     object const & input,
                     object const & output) ;

  static object make();

};
}
}
}

constructors

struct example_unary_ufunc
{
  typedef any_valid_type argument_type;
  typedef any_valid_type 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 TUnaryFunctor,
          typename TArgument=typename TUnaryFunctor::argument_type,
          typename TResult=typename TUnaryFunctor::result_type>
static object call(TUnaryFunctor & self,
                   object const & input,
                   object const & output);
Requires:

Typenames TUnaryFunctor and optionally TArgument for argument type and TResult for result type

Effects:

Passes a Python object to the underlying C++ functor after broadcasting its arguments

template <typename TUnaryFunctor,
          typename TArgument=typename TUnaryFunctor::argument_type,
          typename TResult=typename TUnaryFunctor::result_type>
static object make();
Requires:

Typenames TUnaryFunctor and optionally TArgument 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 UnarySquare
{
  typedef double argument_type;
  typedef double result_type;
  double operator()(double r) const { return r * r;}
};

p::object ud = p::class_<UnarySquare, boost::shared_ptr<UnarySquare> >("UnarySquare").def("__call__", np::unary_ufunc<UnarySquare>::make());
p::object inst = ud();
std::cout << "Square of unary scalar 1.0 is " << p::extract <char const * > (p::str(inst.attr("__call__")(1.0))) << std::endl ;
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