Re: [boost] [fit] Mini Review (consider 1/2 or 1/4 weight)

Subject: Re: [boost] [fit] Mini Review (consider 1/2 or 1/4 weight)
From: paul Fultz (pfultz2_at_[hidden])
Date: 2016-03-20 17:22:27

> On Sunday, March 20, 2016 8:11 AM, Gonzalo BG <gonzalobg88_at_[hidden]> wrote:
> > I want to make a minor remark about this:
> 
>>  [...]
>> 
>>  1. Inline functions are weak symbols and don't violate ODR
>>  2. Static variables in C++ do violate ODR (btw in C they do not) so
>>  basically you COPY every instance of the functions across compilation
>>  unit.
>> 
>>  [...]
> 
> FIT (and range-v3, and many other libraries) follow the best practice we
> currently have in C++ < 17 here, which is Eric Niebler's N4381 Suggested
> Design for Customization Points [0].
> 
> It seems, however, that from the discussion here and in the other reviews
> of FIT, this best practice is not "common practice" yet.
> 
> The failure is only on us for not giving it enough exposure.
> 
> IMO all new Boost libraries should be following N4381 as FIT does.
> 
> On first encounter, however, a macro like BOOST_FIT_STATIC_LAMBDA
> is going to look very suspicious: why is this required? what about ODR? ...
> 
> Since these macros are going to remain the only viable solution for
> a long time (until we drop support for C++<17) we should address these
> questions on first usage in the documentation of new libraries, maybe by
> linking against N4381 directly (which addresses the issue in great detail)
> or by providing a small summary of N4381 in the documentation or the

> Boost wiki.

I agree and plan to add this to the documentation.

> 
> [0]
> http://ericniebler.github.io/std/wg21/D4381.html#no-violations-of-the-one-definition-rule
> 
> 
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