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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?
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std::ref. Constructs an object of the appropriate reference_wrapper type to hold a reference to elem . If the argument is itself a reference_wrapper (2), it creates a copy of x instead. The function calls the proper reference_wrapper constructor.
References in C++ When a variable is declared as a reference, it becomes an alternative name for an existing variable. A variable can be declared as a reference by putting '&' in the declaration.
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. :)
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