Re: [boost] [c++11]

Subject: Re: [boost] [c++11]
From: Niall Douglas (ndouglas_at_[hidden])
Date: 2013-06-17 18:03:49

> > I should quickly explain why rvalue ref support is so important to
proposed
> > Boost.AFIO: it's a 100% batch API and therefore takes in batches of
things
> > to do and returns out batches of results. That implies lots of passing
> > sequences of things around in STL containers, which without rvalue refs
are
> > not cheap to copy. Therefore while we could get the library working on
> 
> Maybe BOOST_ASIO_MOVE_ARG (in boost/asio/detail/config.hpp) will work
> for you.

I don't understand how that makes std::vector<> or any other STL container
suddenly magically start not copy constructing its contents on C++03
compilers.

struct async_io_op has both rvalue and const lvalue copy and assignment
constructors. It's left up to the compiler and STL container implementation
to decide when and where to use them. I agree we should be using more
std::move() to help the compiler where it needs it, but all performance
tuning is being left till after the Boost import.

Niall

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