On 4/27/23 18:16, Peter Dimov via Boost wrote:

Newer C++ standards (20) have been adding useful things to the standard library (<bit>, <latch>, etc) and most of us would like to use them, both in Boost and outside of it, while still supporting C++11, or 14, or 17.

Many of these components are straightforward to implement using the C++11 standard library, consist of not much than one relatively small header, don't need many Boost dependencies beyond the required ones (Assert, ThrowException, Config), and since their interface is already fixed by the standard, don't need a design review.

It would be nice if we had a dedicated place in Boost where to put these, to avoid the need for everyone reimplementing a private copy.

At the moment, some of these have gone into Core, for lack of anywhere else, and we now have a <latch> contribution (which I encouraged):

https://github.com/boostorg/core/pull/144

However, Core is not quite the right place for these components.

So my suggestion is to create a separate library/repo, Boost.Compat (boostorg/compat, namespace boost::compat) for them.

Thoughts? (Be sure to read the discussion in the PR as well.)

My main concern in the aforementioned PR was increased code duplication, and it isn't fixed by having Boost.Compat. I really don't like us having multiple copies of the same components for the sole purpose of reducing dependencies (in the case of latch - reducing tests dependencies, not even library dependencies). If we don't want to use the libraries we write and accept during the review then there must be something wrong with Boost. This isn't good for Boost (more maintenance required, less overall quality because some parts are left unmaintained) and this isn't good for users (more confusion, more compatibility issues). Secondly, I'm not sure I like the idea of another kitchen sink kind of library a-la Boost.Core and Boost.Utility, as such libraries tend to become bloated over time. Such libraries are also inconvenient for users' consumption, as it is more difficult to find a component in one of such libraries compared to in one of the specialized ones. I would prefer us to keep evolving our existing libraries, where appropriate, and accept new ones, where their functionality is not covered by the existing ones. And lastly. I realize that the proposed Boost.Compat is supposed to contain direct equivalents of the standard components. But what if we want to improve on that? Would this be not allowed simply because this would deviate from the standard? If allowed, would this still not require a review? I think, the "no review required" policy might be a bit too permissive.