eliaskosunen/scnlib

Header only build is too complex

igormcoelho opened this issue · 1 comments

igormcoelho commented

Normally, adding Header Only libraries only require including the include folder.
See FMT library:

FMT_DIR=external/fmt-9.1.0
INCLUDES=-I$(FMT_DIR)/include
DEFINES=-DFMT_HEADER_ONLY

With SCN library, multiple things are necessary, including, to include the src/ directory, which is quite strange... also, manually including thirdparty libraries also makes it even more complex.

SCN_DIR=external/scn-1.1.2
INCLUDES=-I$(SCN_DIR)/include -I$(SCN_DIR)/src -I$(SCN_DIR)/src/deps/fast_float/single_include
DEFINES= -DSCN_HEADER_ONLY

So, my suggestions are:

  1. if possible, only include "includable" things on include/ folder, not on src/ folder.
  2. if possible, automatically add the dependency when SCN_HEADER_ONLY is defined... something like:
// on some important src/ file that depends on fast_float...
#ifdef SCN_HEADER_ONLY
#include "deps/fast_float/single_include/fast_float.h"
#endif
  1. if possible, create a define HEADER_ONLY that defines SCN_HEADER_ONLY
#ifdef  HEADER_ONLY
#define SCN_HEADER_ONLY
#endif

If something like this existed, maybe even on FMT, then projects that depend on header only configurations would be make so much simpler, by simply defining "HEADER_ONLY", and everybody defines their own specific header only definitions.

One solution used by CATCH2 project is to manually build an "amalgamated" header file, that includes headers and sources together... so it could possibly be distributed together with versioned builds of this library, thus removing the need to include src/ and deps.

I mean, the project currently work fine and these are all suggestions, to make it simpler for adoption when CMake or other build systems are not used (maybe in very tiny or demonstration projects). Congratulations for this nice library!

eliaskosunen commented

Thank you for your suggestion! However, I don't think I'll be touching the header-only builds: as you said, they work fine-ish now, and they are a workaround anyway for the mess that is dependency management in C++. It's very easy to also accidentally blow up your compile times when using the header only mode.

For that reason, I've removed header-only mode from v2, and will leave it be for v1. But, as I said, thanks anyway!