How is tr1::reference_wrapper useful?

Question

recently I've been reading through Scott Meyers's excellent Effective C++ book. In one of the last tips he covered some of the features from TR1 - I knew many of them via Boost.

However, there was one that I definitely did NOT recognize: tr1::reference_wrapper.

How and when would I use tr1::reference_wrapper?

Answer 1

It's like boost::ref, as far as I know. Basically, a reference which can be copied. Very useful when binding to functions where you need to pass parameters by reference.

For example (using boost syntax):

void Increment( int& iValue )
{
    iValue++;
}

int iVariable = 0;
boost::function< void () > fIncrementMyVariable = boost::bind( &Increment, boost::ref( iVariable ));

fIncrementMyVariable();

This Dr. Dobbs article has some info.

Hope this is right, and helpful. :)