emplace, scope, enforce [Was: Re: Manual...]

[Andrei Alexandrescu]

On 07/21/2010 03:35 PM, Dmitry Olshansky wrote:
> Thanks for kind feedback (and showing some optimization tricks). Also
> this implementation still has issues with it: it calls dtor twice. Not a
> good trait for RAII technique ! :)
> Since it's now considered useful I feel myself obliged to enhance and
> correct it. Sadly enough I still haven't managed to apply an inner
> template trick.
> Here's the end result along with a simple unittest:
[snip]

The double destructor hits a bug in the compiler implementation. Anyway, 
here's the committed code:

http://www.dsource.org/projects/phobos/changeset/1774

It uses a new idiom that is enabled by auto returns - defines a struct 
inside the function and returns it. That's a veritable existential type! 
(http://stackoverflow.com/questions/292274/what-is-an-existential-type) 
I expect more of that idiom in the upcoming commits.


Andrei