Recently, while watching the GoingNative conference, I learned about the new std::shared_ptr helper function std::make_shared.
In the talk Stephan T. Lavavej discusses the performance improvements they’ve made. It seems std::make_shared can save a few extra allocations and a bit of memory overhead. This can be significant if you dynamically create lots of objects. Back in the real world I found myself wondering if boost supported this little gem for boost::shared_ptr. Seems it does. And has since 1.39.0 in 2009. How is it possible that I’ve overlooked this? Example usage: Instead of doing this:
boost::shared_ptr ptr(new MyClass(param1, param2));
std::shared_ptr ptr2(new MyClass(param1, param2));
Do this:
boost::shared_ptr ptr = boost::make_shared(param1, param2);
std::shared_ptr ptr2 = std::make_shared(param1, param2);
Where this really shines is if you have a function expecting a shared_ptr.
void somefunc(const std::shared_ptr &ptr);
// Instead of this:
somefunc(std::shared_ptr(new MyClass(param1, param2)));
// do this:
somefunc(std::make_shared(param1, param2));
Similar functions exist for the other types of smart pointers. Related boost docs are here.