On 17/12/2024 02:37, Chuanqi Xu via Boost wrote:
Hi Boost Developers, I am Chuanqi Xu, the maintainer for modules & serialization in clang and also a fan of C++20 modules. The post itself was motivated by a discussion (https://cpplang.slack.com/archives/C27KZLB0X/p1734335425348809 <https://cpplang.slack.com/archives/C27KZLB0X/p1734335425348809 >). You don’t need to read it if you’re not interested. I’ll try to make the post itself self contained.
I *think* at present I would prefer to see library-level support - ie clients would do a: import boost.whatever; rather than a single monolithic: import boost; In any case multiple libraries can be always be grouped together in a "super-module" that import-exports all of them. There are some advantages to this: * it's modular and can grow gradually based on demand. * We don't get blocked by if library X explodes all current compilers (there's some complex code in Boost after all). FYI regex currently has an experimental branch which does this - I really should have got it into the last release, basically I just need to document things. I would also add that it's not really as straightforward as you might think - compilers are certainly getting better in this regard - but there are all sorts of traps especially if client code mixes imports with #includes of regex's std lib dependencies. I also had to do quite a bit of work (real code changes) to ensure that module builds were actually faster in practice than a simple header-only approach. Given the template-heavy nature of Boost I would imagine that many libraries would be in this situation. And finally.... build systems *currently* are not up to the job.... if I merged the regex module support now that would leave users with a very 1980's "here's some code files, build them yourself" kind of situation. Best, John.