id,summary,reporter,owner,description,type,status,milestone,component,version,severity,resolution,keywords,cc
7330,Patch adding move constructors and move assignments,Antony Polukhin,Douglas Gregor,"Use of move constructor and move assignment reduce memory allocation/deallocations count and do not call functor copy operator for big functors.
Example:
{{{
struct big_aggregating_structure {
    int disable_small_objects_optimizations[32];
    
    void operator()() {}
};

...

function<void()> f1 = big_aggregating_structure();
function<void()> f2 = f1; // will call new, copy()
function<void()> f3 = std::move(f1); // Just swaps pointers, leaves f1 empty
f3 = f2; // Will call new, copy(), destory(), delete
f3 = std::move(f2); // Just swaps pointers, leaves f2 empty (calls destory(), delete for f3)

{
    function<void()> f_new1 = big_aggregating_structure();
    function<void()> f_new2 = std::move(f_new1);
    // Without move constructor, there will be additional new, copy(), destroy(), delete calls
}

}}}

This patch could be very usefull for boost::asio, boost::thread and anyone, who uses boost::function in STL containers on C++11 compilers.
Patch was tested on MSVC2010, GCC-4.6",Patches,closed,To Be Determined,function,Boost Development Trunk,Optimization,fixed,,