Re: [boost] [mpl] Abandoning old compilers

Subject: Re: [boost] [mpl] Abandoning old compilers
From: Edward Diener (eldiener_at_[hidden])
Date: 2015-02-28 22:20:52

On 2/28/2015 6:28 PM, Robert Ramey wrote:
> Edward Diener-3 wrote
>> My reason for supporting the changes for MPL which Stephen Kelly wanted
>> to make is that hackery, no matter how brilliant, for compilers whose
>> support for the C++ standard is poor in some way tends to obfuscate the
>> understanding of how code works. If said compilers are outdated and have
>> been superceded by newer versions which the vast majority of programmers
>> now use, or if the compiler is not supported or marketed anymore, I can
>> understand dropping such workarounds rather than carrying them around
>> forever. Code then become easier to understand and change. One does not
>> have to worry about some old compiler which no one rationally should be
>> using when making additions or changes to a library.
>
> I think we're mixing a couple of things here.  Stephen's changes were
> not just one library he was willing to maintain and take responsibility
> for, but the whole of boost.

When I spoke of Stephen Kelly's change I meant only those for MPL.

>  No one could be responsible for that.  I
> think he underestimated the subtle repercussions of changes which
> which seemed at first glance to be innocuous.  In his defense, I think
> that is very easy to do since a of the hackery is as non-obvious as it
> is necessary.  So let's set Stephen's changes apart from this discussion.
>
> The maintainer has to have the option of doing things in the way he
> thinks is most expedient.  In some cases, that will mean just leaving
> things as they are, and other cases that will mean throwing out an
> implementation of some feature and replacing it with a simpler one
> which is easier to maintain and verify.  No one can make an a-priori
> policy for that.

I was not promoting some a-priori policy, only arguing that the removal 
of support in MPL for compilers which are ancient, non-conforming, and 
barely usable in creating modern C++ code is a viable goal in order to 
make MPL more easily understandable.

I agree with you that whoever makes changes to any library is 
responsible for seeing through those changes. I do not agree with you 
that this can only be done if a library has a single maintainer in 
charge of everything. The latter may be a laudatory goal and I do think 
that the creator of a library if he is still active makes the final call 
on changes, but the creator(s) of MPL are no longer active on Boost and 
maintaining the library. Do we then say that because a library no longer 
has a primary maintainer who created the library that no changes to the 
library except for bug fixes should ever be made ? That is very 
unrealistic consider that very few creators of a library are willing to 
maintain that library perpetually, which is only natural.