> I do not understand this comment, as I have done separate compilation every day with C++ for over two two decades: the model inherently only allows this, as every translation unit absolutely must be compiled separately and then linked... you don't even have a choice in the matter.
Except if your headers include macros or templates, which must be evaluated every time. This is not separate compilation. What C/C++ developers have been doing for 20 years is jumping through hoops to incrementally reuse previously compiled results because C/C++ violate basic modularity principles [1]. They call it "separate compilation", but it's a pale shadow of true separate compilation.
Proper modules would enforce abstraction boundaries so true separate compilation becomes possible. I can't speak to the specific C++ proposal here, but enabling separate compilation is exactly what modules are for.
Normally use of templates do break separate compilation but it can be recovered, and it is routinely done on large codebases, via explicit template instantiation. The ergonomics are not great of course and hopefully modules will improve things.
Except if your headers include macros or templates, which must be evaluated every time. This is not separate compilation. What C/C++ developers have been doing for 20 years is jumping through hoops to incrementally reuse previously compiled results because C/C++ violate basic modularity principles [1]. They call it "separate compilation", but it's a pale shadow of true separate compilation.
Proper modules would enforce abstraction boundaries so true separate compilation becomes possible. I can't speak to the specific C++ proposal here, but enabling separate compilation is exactly what modules are for.
[1] http://llvm.org/devmtg/2012-11/Gregor-Modules.pdf