Re: [boost] [variant] Please vote for behavior (Was: Basic rvalue and C++11 features seupport)

Subject: Re: [boost] [variant] Please vote for behavior (Was: Basic rvalue and C++11 features seupport)
From: Andrey Semashev (andrey.semashev_at_[hidden])
Date: 2013-01-21 12:34:29

On Monday 21 January 2013 19:06:32 Paul Smith wrote:
> On Mon, Jan 21, 2013 at 6:12 PM, Joel de Guzman <djowel_at_[hidden]> wrote:
> > This notion of a "valid" state
> > is not clear to begin with anyway and many say it depends on the library
> > to define what "valid" means. The case of NaN is a very clear example
> > of a perfectly "valid" state similar to what we have here.
> 
> I'm not sure what the NaN example supposed to convey? I think Nevin
> brought it up to show that std::less<double> is not a weak partial
> order. And guess what, it technically isn't! Try to put NaNs inside an
> associative container and watch the world collapse. The big difference
> is that no operation on non-NaNs that the container performs ever
> produces a NaN out of thin air.

Why would a container try to order moved-from elements?