Re: [boost] [GSoC] [Boost.Hana] Formal review request

Subject: Re: [boost] [GSoC] [Boost.Hana] Formal review request
From: Roland Bock (rbock_at_[hidden])
Date: 2014-08-04 00:28:56

On 2014-08-03 22:16, Niall Douglas wrote:
> On 3 Aug 2014 at 8:48, Robert Ramey wrote:
>
>> My real goal is to convince the C++ community that any library which
>> includes templates as part of the user interface must have explicit type
>> constraints in order to be considered for formal review.  I want to see
>> type constraints be understood and appreciated by the C++ user community
>> in general rather than a small group who spend years disputing how to
>> implement the idea. 
> I strongly disagree with this idea if by "type constraints" you mean 
> "error out if it doesn't fit" which apparently you do.
Hmm? If the arguments do not fit, an error is required. The kind of
error is debatable. As Paul points out, a hard error like static_assert
is too strong if you want to use it with SFINAE.

But there has to be an error of some kind if the arguments don't fit.

>  That isn't 
> really concepts at all in my opinion, it's just some sort of super 
> static assert.
It really depends on the kind of error you produce. Afaict Concepts Lite
will create SFINAE-compatible errors.

Cheers,

Roland