[boost] [any] Multimethod for boost::any

Subject: [boost] [any] Multimethod for boost::any
From: Nowake (nowake_at_[hidden])
Date: 2009-02-20 06:58:57

Hi,

I update Multimethod.
I make Multimethod::ApplyTraits to control method's dispatching.
https://svn.boost.org/trac/boost/attachment/ticket/2749/Multimethod.4.hpp

Samples:
______________________________________________________________________

struct Method10 { // MultiMethod
   string operator()(const int a) const {
      return string("int: "+lexical_cast<string>(a));
   };
   string operator()(const double a) const {
      return string("double: "+lexical_cast<string>(a));
   };
};
struct Method11 : public Method10 {};

struct Apply10 {  // ApplyTraits to change int <-> double
   template<typename A00>
   string operator()(A00& a00, const double a01) {
      return a00(static_cast<int>(a01));
   };
   template<typename A00>
   string operator()(A00& a00, const int a01) {
      return a00(static_cast<double>(a01));
   };
};

// you can set ApplyTraits to each type combination.
// custom ApplyTraits
bool m10(Multimethod::entry<string, any, Method10, const int>(Apply10()));
bool m11(Multimethod::entry<string, any, Method10, const double>(Apply10()));

// use default ApplyTraits
bool m12(Multimethod::entry<string, any, Method11, const int>());
bool m13(Multimethod::entry<string, any, Method11, const double>());

BOOST_AUTO_TEST_CASE(test01) {
   Method10 m10;
   any mm(m10);
   BOOST_CHECK_EQUAL(Multimethod::apply<string>(mm,   1), "double: 1");
   BOOST_CHECK_EQUAL(Multimethod::apply<string>(mm, 1.0), "int: 1");

   Method11 m11;
   mm = m11;
   BOOST_CHECK_EQUAL(Multimethod::apply<string>(mm,   1), "int: 1");
   BOOST_CHECK_EQUAL(Multimethod::apply<string>(mm, 1.0), "double: 1");
}

// you can also use ApplyTraits to fit functions to multi methods.

struct Method00 { // MultiMethod
   string operator()() const { return string("string()"); };
};
struct Apply00 {  // ApplyTraits
   template<typename A00>
   shared_ptr<any> operator()(A00& a00) {
      return shared_ptr<any>(new any(a00()));
   };
};
// entry Method00::operator()() with ApplyTraits
bool m00(Multimethod::entry<shared_ptr<any>, any, Method00>(Apply00()));

BOOST_AUTO_TEST_CASE(test00) {
   Method00 m;
   any mm(m);
   shared_ptr<any> r(Multimethod::apply<shared_ptr<any> >(mm));
   BOOST_CHECK_EQUAL(any_cast<string>(*r), "string()"); 
}
_____________________________________________________________________

Regrads. 
Nowake