Re: STL map containing pointer_to_binary_function

From:

"Glennmac@gmail.com" <Glennmac@gmail.com>

Newsgroups:

comp.lang.c++

Date:

Wed, 29 Aug 2007 19:15:43 -0000

Message-ID:

<1188414943.747409.321180@r29g2000hsg.googlegroups.com>

Barry,

Thanks for the help. I have been working on a different method to do
this, but have hit the same results.

I have created a base class:

template <typename T>
class base {
public:
base(T eval) :
  mValue(eval)
{};

virtual ~base() {};

bool run(const string &actualValue) {
   runInternal(mValue, actualValue);
}

protected:
virtual bool runInternal(int v1, const string &v2) = 0;
virtual bool runInternal(const string &v1, const string &v2) = 0;

protected:
T mValue;
};

template <typename T>
class d1 : public base<T> {
public:
d1(T eval) :
  base<T>(eval)
{};

private:
bool runInternal(int v1, const string &v2) {
  // convert string to int
  return v1 == v2;
};

bool runInternal(const string &v1, const string &v2) {
  return v1 == v2;
};
};

As I am sure you can see, I can not create a map<string, base *>
because base needs a type at that point. Can I somehow use a template
function in the class and not a complete template class?

Basically I need to have a map of functions, classes whatever that
test <, > and == of a known value and actual value. They can be
strings, int, and doubles. Is this possible?

Thanks

Glenn

On Aug 29, 10:28 am, Barry <dhb2...@gmail.com> wrote:

Glenn...@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