the FOREACH macro

Hi,

I would like to do something like this, which is the WISH case:


I already can do something similar, which is the ALREADY-HAVE case:


with a macro that I defined this way (inspired by the iteration macros
in the Boost Graph Library):

The complete source code for the example above is at the bottom of this
message.

You may rightfully argue that this macro makes little sense, because
you can just have a regular loop there. However, in my real code
(what I gave you here is just a show case) there are two loops and I
want to put then into a macro.

Now, the problem is that I can't declare in the for-loop the variables
key and value as shown in the WISH case. I don't have this problem in
the ALREADY-HAVE case, becasue I only have to declare an iterator.

Thanks for reading. Any ideas how to get closer to my WISH case?

Thanks & best,
Irek

*********************************************

#include <iostream>
#include <map>

#define FOREACH(MNAME, INAME, MapType) \
  for (MapType::iterator \
     INAME = MNAME.begin(); INAME != MNAME.end(); ++INAME)

using namespace std;

typedef map<int, double> hash;

int main()
{
  hash a;

  a[0] = 1.71;
  a[1] = 3.14;

  FOREACH(a, i, hash)
    cout << i->first << "->" << i->second << "\n";

  return 0;
}

--
      [ See http://www.gotw.ca/resources/clcm.htm for info about ]
      [ comp.lang.c++.moderated. First time posters: Do this! ]