[Boost-users] Why is cref required in this nested bind example?

Subject: [Boost-users] Why is cref required in this nested bind example?
From: Chris Stankevitz (chrisstankevitz_at_[hidden])
Date: 2012-12-04 18:02:34

Hello,

Can someone please explain why a cref is needed in the last line of
the attached code snippet?

Thank you,

Chris

===

#include <boost/bind.hpp>
#include <boost/function.hpp>

using boost::bind;
using boost::cref;
using boost::function;

void a()
{
}

void b(function<void()>)
{
}

void f()
{
//bind(b, bind(a));
  bind(b, cref(bind(a)));
}