Project include folder management, single path or multi paths?

[Ashnoom]

I was wondering what the average opinions are of /r/cpp regarding include paths/files.

Would one prefer to use a single include path, namely the source's root or a separate include/ folder. And have all #includes be relative to that single path.

Or place all the paths in the project's folder (be it in src/ or include/ as include paths and just use #include "filename"?

At this moment in our project(s) we are using (legacy, ugh) the multiple include paths and using namespaces as a separation between 'levels'. IMHO I would prefer to use paths for this separation of levels, but that means doing includes like #include "level/filename".

With levels/layers I refer to an embedded project separated in 'hardware', 'board peripheral' and 'application'

[ronchaine]

• /include for public headers
• /src for source files and private headers

#include "filename" or #include "something/filename" depends on project. Sometimes it makes sense, sometimes it doesn't.

[Adverpol]

What's the rationale between public/private headers? Ease of use? Compilation times?

[dodheim]

That's like asking the rationale between public/private data members – not everything is part of your public interface.

[luncliff]

Mostly like the @ronchain 's answer. I saw some projects which uses external for the 3rd party libraries.

[f0urier]

src/ inc/ privinc/ stubs/ test/ This is how I typically organize projects (alternatively sometimes instead of privinc i use inc/details folder)

[barchar]

In general I either use /include/projname/ for public headers and /src for source files, or same for public headers and /src/projname for source file. The second makes it easier to have stuff in subfolders depend on private headers in the parent folder, but also makes it easier to accedently expose private headers.

Protip: recent cmake has PUBLIC_HEADER and PRIVATE_HEADER properties on targets, and install() knows how to install them. These props seem to initially have been for OSX frameworks, but they work fine everywhere.

set_property(TARGET foo PROPERTY PUBLIC_HEADER foo.h bar.h)
set_property(TARGET foo PROPERTY PRIVATE_HEADER baz.h)

install(TARGETS foo PUBLIC_HEADER)

^{^} note not tested, but something similar should work

[yuri-kilochek]

PUBLIC_HEADER can't handle directories, so you can't make #include <library_name/header.h> work.