Add support for non-header-only mode?

[p0358]

A bunch of primarily header-only libraries like tomlplusplus or spdlog are also available in a compilable variant, where there's a single translation unit (cpp file) that defines the body of actual functions, or even a separate project that generates a library with the symbols, and on other places they are just declared and reused. They claim that it speeds up the compilation a lot (and it makes sense, given the size of the headers, and reusability of compiled code increases due to incremental compilation). The idea is simple, some preprocessor directives should control whether the header only declares all the functions, or whether it also defines their bodies. And the include with definitions should just go into one designated file, while the lightweight declare-only inclusion to all the other files.

Also Boost.Asio has something like this for instance (depending on whether library is to be in .cpp or separate lib):

Optional separate compilation
By default, Boost.Asio is a header-only library. However, some developers may prefer to build Boost.Asio using separately compiled source code. To do this, add #include <boost/asio/impl/src.hpp> to one (and only one) source file in a program, then build the program with BOOST_ASIO_SEPARATE_COMPILATION defined in the project/compiler settings. Alternatively, BOOST_ASIO_DYN_LINK may be defined to build a separately-compiled Boost.Asio as part of a shared library.

[d99kris]

Thanks for the suggestion.

Generally I think that header-only implementations should be avoided for the reasons you pointed out.

However, in the case of rapidcsv the library is heavily using templates and templates generally need to be in the header-file, so there is not that much benefit providing a non-header-only version. I did consider it before and ended up not implementing it. However with this discussion thread we can gauge the interest and see if there are more people needing this.

Thanks for the Boost example. Actually I have another open source project spacy-cpp which is available both as header-only and as a compiled library, so I'm familiar with the concept.

[d99kris]

I will proceed to close this discussion, as there are no plans to address this.