Ruben Perez wrote:
Hi all,
I finally have something workable regarding Boost and C++20 modules. I've described it in detail in this article [1], but here's a rough summary:
I've modularized Boost.Mp11 [2] (as an example of a header-only library) and Boost.Charconv [3] (as an example of a compiled library). ... Other than that, I'd like to get some feedback on this, and whether you think this proposal is worth the effort.
I looked at the Mp11 patch, and I think I don't quite like this approach. At present, user code needs to look like this #ifdef BOOST_USE_MODULES import boost.mp11; import boost.core; import std; #else #include <boost/mp11/this.hpp> #include <boost/core/that.hpp> #include <standard_header> #endif and I'm not sure that this is what we want. Rather, my current thinking is that we want this for user code: #include <boost/mp11/this.hpp> #include <boost/core/that.hpp> #include <standard_header> with boost/mp11/this.hpp being #ifdef BOOST_USE_MODULES import boost.mp11; #else #include <boost/mp11/detail/this.hpp> #endif This would presume that <standard_header> does something similar, which is in fact one suggested implementation strategy. If not, we'll need #include <boost/mp11/this.hpp> #include <boost/core/that.hpp> #include <boost/std/standard_header.hpp> which is not ideal, but is still better than what we started with. In the general case (when a header also defines macros), the public header will contain both import boost.mp11; and the part that defines the macros, which in Mp11's case is #include <boost/mp11/version.hpp> User code wouldn't need to know that in addition to the import, it also needs to include a separate macro header.