Subject: Re: [boost] [system] The new Boost.System is now ready
From: Gavin Lambert (boost_at_[hidden])
Date: 2018-10-07 23:30:33
On 5/10/2018 11:37, Peter Dimov wrote:
>> The new Boost.System is now complete, on the develop branch:
>>
>> https://www.boost.org/doc/libs/develop/libs/system/
>>
>> - header-only
>> - even more constexpr than 1.68
>
> https://pdimov.github.io/cpp-papers/P1195R0.html
>
>> - identifier-based category comparison
>
> https://pdimov.github.io/cpp-papers/P1196R0.html
>
>> - message() into a caller-supplied buffer
>
> https://pdimov.github.io/cpp-papers/P1197R0.html
>
>> - failed()
>
> https://pdimov.github.io/cpp-papers/P1198R0.html
>
>> The plan is to merge it to master at some point if no breakage is
>> encountered on develop, so that it can go into the next release.
Looks good.
I assume that the link to random.org implies that the proposed
identifiers for generic_category and system_category were selected this way.
I suggest calling this out a bit more explicitly as the preferred method
of choosing identifiers for custom categories, as on the first reading I
overlooked this and was wondering how they had been chosen. I also
suspect that unless strongly encouraged to pick only random numbers,
people are going to naturally try to pick "cute" identifiers (eg. ASCII
encodings of words, a la FOURCC) or dumb identifiers (small integers),
which have a much higher probability of collision.
Also, in P1197R0, perhaps I'm missing some context (not having a copy of
the standard handy) but it seems peculiar that the Effects of the two
new message() overloads are ordered differently with respect to possibly
returning a literal message pointer, ignoring buffer and len. Why is it
that the second can do this but not the first?