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Subject: [boost] Thoughts on Boost v2 (was: Re: Is Boost dead? [Re: Anyone is interested in being review manager of ‘Application’?])
From: Niall Douglas (s_sourceforge_at_[hidden])
Date: 2014-05-16 13:10:51

On 16 May 2014 at 17:46, Stephen Kelly wrote:

> There is clearly not agreement within Boost that anything should be done at
> all regarding modularization, before a more 'big bang' break forward, from a
> reading of the mail from Niall.

For the purposes of clarity, I am not a member of Boost. I do not sit
on any committees, and have no representation nor standing with the
community apart from doing some admin for GSoC. I would say that my
opinions on this are so extreme that no one agrees with me, and I
expect my presentation at C++ Now tomorrow to not be popular.

I have however been doing a lot of canvassing whilst here at C++ Now.
The main problems with Boost which are causing its decline are these:

1. Boost isn't sexy any more. As one very highly respected world
famous engineer put it - and I won't say who, and I apologise to him
for stealing his words without attribution:

"Boost used to be about all the stuff you really wanted in the
standard. Now Boost looks like all the stuff that wasn't good enough
to get into the standard"

2. Everyone recognises there are serious problems with process,
everything from how you were treated Stephen when you tried cleaning
out cruft and only really Dave supported you, right through to the
fact that peer review simply doesn't work any more. The Boost
community has become quite selfish in recent years, as you would
expect from those with a vested interest in the status quo before
evolution. And for the record, I have no problem with those vested
interests keeping their existing Boost, but I personally want as far
away from C++ 03 as soon as is possible.

3. All the interesting new C++ 11 libraries you find around the
internet have zero interest in trying to join Boost, with a very few
honorable exceptions. That speaks volumes, to me at least.

Which suggests to me a need for a new Boost which attempts to apply
the benefits of hindsight to what we learned with Boost v1. Now, it
is extremely clear from this conference there is little appetite for
that, but I think later on this year we're going to have three C++11
libraries in the queue, and if things have not very significantly
progressed in any of the three items above, I think that time will be
right time to fork. And here is what I think should be in a fork of

1. Minimum required compiler feature set will be VS2014's. No use of
Boost STL permitted where the C++ 11 STL provides a feature.

2. cmake instead of Boost.Build.

3. Eliminate peer review in favour of a suite of automated libclang
based AST analysers. Instead of persuading people to review
libraries, persuade them to review and improve the AST analysers.

4. Mandatory cross platform per-commit CI with unit testing exceeding
95% coverage. We don't care what unit test library is used so long as
it can output results Jenkins can understand.

5. Mandatory all green thread, memory, UB sanitisers and clean
valgrind. All also tested per-commit.

6. Mandatory CI testing for exception safety. I am hoping a clang
rewriter can basically patch all exception throws and have them
randomly throw for testing.

7. Per-library source distributions instead of a monolithic blob.
This implies some dependency management, but cmake makes that much
easier. It also means we can eliminate the release cycle because each
library does its own release cycle, and the correct (i.e. tested)
version of dependencies are included into each per-library source
distro. This solves the version lock problem currently plaguing
git-ised Boost, at the cost of pushing the version lock problem onto
users [1]. BTW I want to see a soak test of the unit tests for 24
hours be all green before a release.

8. Reusable utilities in a submitted library need merging into some
common utilities library which follows the STL conventions. Other
than that, no source code, naming conventions, namespace or anything
else needs converting or changing. We are looking for very high
quality C++ libraries, nothing more. Obviously if someone hopes for a
library to enter the C++ 17 STL they'll need much more rigour, but
that's up to them.

9. There is no longer an "in" or an "out" for distribution. I'm
thinking of a scorecard page where member libraries are ranked by how
high quality they are according to all the automated review, so when
I say "mandatory" above, I simply mean they don't get to appear on
the main downloads page without that precondition. All submitted
libraries do appear though, just ranked very low if their quality is
low. I would hope all this is generated from a database and requires
very little human input.

10. BoostBook documentation using the Boost look and feel becomes
mandatory. I've had enough with library authors thinking they can
improve on BoostBook's output with things like using Comic Sans as
the font or weird colour schemes throughout.

So, basically, in some areas requirements are significantly
tightened. In other areas requirements are significantly loosened.
The aims of the above ten items are as follows:

1. To reduce the amount of human work involved in maintaining Boost.
What Dave and Daniel had to do for the git conversion last year was
far above what anyone should ever feel they need to do.

2. To decentralise Boost, letting it scale up far better.

3. To provide a gradual process of entering Boost which authors can
tip away at slowly with automated scripts slowly improving their
rankings instead of the current "lumps" of high intensity output and
the review approved/failed scheme currently used.

4. To incentivise authors to maintain their libraries as the quality
bar is improved - the automated scripts will start to drop library
rankings as the quality is raised, thus dropping that library in the
overall rankings. Rather more importantly, it provides a natural
"deprecation" mechanism, something sorely lacking in my opinion from
present Boost.


[1]: If this model proves popular as we can get a regular donation
stream going, we could deploy an automated SHA stamper which through
unit test iteration, figures out which SHAs in which combinations of
libraries are compatible. Then you could safely mix library A's
distro with library B's distro. I'd imagine Debian upstream et al
might be coaxed into providing for this as they need one unified set
of compatible libraries.


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