[CMake] CMake: using dlopen

[Franck Houssen]

----- Mail original -----
> De: "Rainer Poisel" <rainer.poisel at gmail.com>
> À: "Franck Houssen" <franck.houssen at inria.fr>
> Envoyé: Dimanche 7 Janvier 2018 19:34:21
> Objet: Re: [CMake] CMake: using dlopen
> 
> Hi,
> 
> On Sun, Jan 7, 2018 at 7:13 PM, Franck Houssen <franck.houssen at inria.fr>
> wrote:
> > Difference between PUBLIC/PRIVATE has never been clear to me (usually I
> > always use PUBLIC).
> > main.cpp includes dlfcn.h and uses it: not sure to get what you meant
> > (PRIVATE is for templates ? when a header include headers ?)
> 
> you are looking for the "Transitive Dependencies" feature of CMake:

OK, I didn't get that. It's more clear to me now. Thanks !

>   *
>   https://cmake.org/cmake/help/v3.0/manual/cmake-buildsystem.7.html#transitive-usage-requirements
> 
> Generally speaking and from my personal experience, use the
> target_-commands as much as possible because properties are bound to
> targets and their dependencies rather than a file/directory structure.
> 
> So, that means, use target_include_directories(),
> target_compile_options(), target_compile_definitions(),
> target_sources(), ... for your targets. The magic keyword to propagate
> the properties of your targets is target_link_libraries(). Depending
> on what scope (PRIVATE, PUBLIC, INTERFACE) the properties have been
> defined using the other target_-commands, the target_link_libraries()
> command propagates these properties to other targets. E. g.
> 
> add_library(otherlib SHARED
>   foo.c
> )
> 
> target_include_directories(otherlib PRIVATE
>   dirPrivate
> )
> 
> target_include_directories(otherlib PUBLIC
>   dirPublic
> )
> 
> add_library(mylib SHARED
>   bar.c
> )
> 
> target_link_libraries(mylib PRIVATE

Is this a typo ?
For the example to work I would have done: target_link_libraries(mylib PUBLIC otherLib), no ? (mylib needs only PUBLIC stuff's from otherLib but not PRIVATE one's). Correct ?


>   otherlib
> )
> 
> In this case, mylib will use all PUBLIC or INTERFACE properties of
> otherlib for its build. Thus, dirPublic will be added to the include
> directory search path for the compilation of bar.c of mylib. PRIVATE
> properties will not be propagated. In the above mentioned example,
> dirPrivate will NOT be added to the include directory search path for
> the compilation of bar.c of mylib.
> 

The example is illustrative (transitivity - PRIVATE is not propagated)

> This is a very short summary, but I hope it is of help to you. There
> are other ressources on the Internet. E. g.
>   *
>   https://stackoverflow.com/questions/26037954/cmake-target-link-libraries-interface-dependencies
>   * https://rix0r.nl/blog/2015/08/13/cmake-guide/
> 
> Regards,
>   Rainer
>