Re: bind2nd, mem_fun, and references

From:
Rolf Magnus <ramagnus@t-online.de>
Newsgroups:
comp.lang.c++
Date:
Sat, 15 Jul 2006 17:47:54 +0200
Message-ID:
<e9b2nb$a13$01$1@news.t-online.com>
Noah Roberts wrote:

Alf P. Steinbach wrote:

* Noah Roberts:

#include <vector>
#include <algorithm>
#include <functional>

class X
{
  int x;
public:
  X(int i) : x(i) {}
  bool eq(const X & other) const { return x == other.x; }
};

int main(int argc, char* argv[])
{
  std::vector<X> xes(10);

  X x(10);

  std::vector<X>::iterator it = std::find_if(xes.begin(), xes.end(),
    std::bind2nd(std::mem_fun(&X::eq), x));

  return 0;
}

Compilation result:

1>c:\program files\microsoft visual studio 8\vc\include\functional(312)
: error C2529: '_Right' : reference to reference is illegal

binder2nd(const _Fn2& _Func,
const typename _Fn2::second_argument_type& _Right)
: op(_Func), value(_Right)
{ // construct from functor and right operand
}

This would follow...

So, what is the correct and portable way to do what I want or is it
just not possible?


One way could be to use to Boost binders (don't know if that works, but
probably, else I would probably have remembered).


That's out until I can convince boss Boost good.

         bool operator==(const X & other) const { return x == other.x; }


That would work except my real-world type is polymorphic.


Well, not in your vector.

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