[boost] [lambda] Binding to templated functions

From: Robert Jones (robertgbjones_at_[hidden])
Date: 2008-07-22 06:00:17

The Boost.Lambda library continues to delight and frustrate me! I have
this code sequence, which is intended to determine whether a predicate
is true for all objects pointed to by the second member of all of
vector of pairs,

#include <utility>
#include <vector>
#include <algorithm>
#include "boost/lambda/lambda.hpp"
#include "boost/lambda/bind.hpp"

struct S
{
  bool predOfS( );
};

int main( )
{
  using namespace std;
  using namespace boost :: lambda;

  typedef pair<int, S *> Pair;
  vector<Pair> pairs;
  bool trueForAll = ( find_if( _1, _2, _3 ) == _2 )(
      pairs.begin( ),
      pairs.end( ),
      ! bind( & S :: predOfS, bind( & Pair :: second, _1 ) ) );
}

The last line gives me compile errors.

Two things:
- I think I need to specicy the template parameters to find_if, but I'm not
sure quite what they are!
- The error message reckons the last arg to find_if is placeholder<4>, not
placeholder<3>, why?

Or maybe there's completely different way to do this kind of thing?

Thanks, Rob.