Re: [epochs] Proposal for an epoch-based organization of Boost libraries

From: Joaquin M López Muñoz (joaquinlopezmunoz_at_[hidden])
Date: 2020-05-24 16:38:28

El 24/05/2020 a las 14:52, Edward Diener via Boost escribió:
> On 5/24/2020 4:20 AM, Joaquin M López Muñoz via Boost wrote:
>> El 23/05/2020 a las 22:46, Edward Diener via Boost escribió:
>>
>>> I am totally against the idea that some code which works perfectly 
>>> in C++03, as well as all
>>> other C++ standard levels, needs to be unnecessarily updated to some 
>>> later C++ standard
>>> level in order to be acceptable to anyone. 
>>
>> This looks somewhat at odds with one of the stated goals of your 
>> cxx_dual lib:
>>
>> "On a more practical basis the CXXD library is for:
>>
>> 1. Programmers writing code not using C++11 syntax who still want to
>> Â Â Â  target some
>> Â Â Â  C++11 libraries if the code is compiled in C++11 mode.
>> Â Â Â  [...]"
>
> I do not see why you think the statement above is at odds with what I 
> previously
> asserted. Whatever might have been added to a Boost library which became a
> C++ standard library in C+11 or beyond could hardly have been done 
> just to add
> unnecessary features. I am not against a library being updated to use 
> features of
> a later C++ standard when those updates are predicated on improving a 
> library
> in specific ways that make it worthwhile to add such features.
>

I'm not sure I'm parsing your sentences right, but does that mean you're ok
with a library using cxx_dual from scracth but not ok if a Boost-reliant 
lib is
later updated via cxx_dual *only* to reduce Boost dependencies in C++11?

> The gist of your proposal which seems to me to be highly flawed is the 
> idea
> that at a certain Epoch level all dependencies of a library must also 
> exist at that
> same Epoch level or higher. How realistic is such a goal ? If library 
> X at Epoch level nnn
> successfully uses library Y at Epoch level nnn-1, why should library Y 
> be arbitrarily updated
> [...]

I understand you meant "should library X be arbitrarily updated" here.

> [...]for no good practical reason to use C++ features of Epoch level nnn ?
>

The reason is to reduce internal Boost dependencies.

> I am pretty sure you can see the absurdity of such a determination as 
> that. 

I admire your confidence but not your perspicacity, as I indeed see no 
absurdity here.

Take for instance Boost.Beast, which depends on boost::string_view but can
be made to depend on std::string_view instead via 
BOOST_BEAST_USE_STD_STRING_VIEW.
Shall I take that you deem this ability absurd?

Joaquín M López Muñoz