on Wed Apr 25 2012, "Stephan T. Lavavej" <stl-AT-exchange.microsoft.com> wrote:
[Mathias Gaunard]
std::shared_ptr is probably optimized for empty or default deleters.
In VC10 and VC11, shared_ptr has five control blocks:
* vanilla * custom deleter * custom deleter and custom allocator * make_shared * allocate_shared
Each is optimally sized (in particular, make_shared/allocate_shared implement the "we know where you live" optimization that I have previously described
I can't find that description. Pointer please?
in an attempt to get Boost to pick it up), except that we don't special-case empty custom deleters/allocators.
You don't need a special case for emptiness if you make them base classes when they're classes (a.k.a. use boost::compressed_pair)
In VC11, we've introduced such special-casing for container allocators/comparators, but we haven't had time to extend it to shared_ptr. I've made a note to myself to do this in the future.
That's what compressed_pair is for; you don't have to keep repeating the same special case over and over ;-) -- Dave Abrahams BoostPro Computing http://www.boostpro.com