Re: STL map containing pointer_to_binary_function

From:

Barry <dhb2000@gmail.com>

Newsgroups:

comp.lang.c++

Date:

Wed, 29 Aug 2007 22:28:46 +0800

Message-ID:

<fb3vrt$fd8$1@aioe.org>

Glennmac@gmail.com wrote:

Thanks for the info.

Let me clearify my goal, I want a map to contain a string as the key
and a function pointer template as the data. Meaning, I want to insert
into the map the following things:

map["test"] = equal_to<string>; // or pointers to the
binary_function....
map["test1"] = equal_to<int>;
map["test2"] = less<double>;

etc...

I know the base template for all those functors is the binary_function
template.

Is it possible to have a map where the data is a binary_function
template?

use boost::any

#include <map>
#include <string>
#include <functional>
#include <algorithm>
#include <iostream>

#include <boost/any.hpp>

using namespace std;
using namespace boost;

struct FunctorDispatcher
{
     void operator() (pair<string, boost::any> const& p) const {
         if (p.first == "less<int>")
         {
             less<int> const* pFnct
                 = boost::any_cast<less<int> >(&(p.second));
             if ((*pFnct)(1, 2))
                 cout << "true" << endl;
         }
         else if (p.first == "equal_to<string>")
         {
             equal_to<string> const* pFnct
                 = boost::any_cast<equal_to<std::string> >(&(p.second));
             if ((*pFnct)("1", "1"))
                 cout << "true" << endl;
         }
     }
};

int main()
{

     map<string, any> functorMap;

     functorMap.insert(make_pair("less<int>", less<int>()));
     functorMap.insert(make_pair("equal_to<string>", equal_to<string>()));

     for_each(functorMap.begin(), functorMap.end(), FunctorDispatcher());
}

--
Thanks
Barry