Best practice for "external libraries" and cmake

[boaks]

Is there a way of "best practice" to prepare cmake files of an "external library".
Especially, if such a library comes already with cmake files or is intended to support other OS as well.

I found also a discussion in issue #8439 but that doesn't include such best practice.

[nashif]

@tejlmand FYI

[boaks]

Thanks for moving. I overseen that "Discussions" are available.

[yashi]

I have been also searching for a best practice. I've written what I learnt while back here https:/yashi/module-sample. I've posted it in discord thread here https://discord.com/channels/720317445772017664/927715693636517958.

[boaks]

I started to prepare my work according to your example.
Unfortunately, I was still busy with other jobs, so I could just start and I'm not ready. I will update this, if I'm done.
Thanks anyway for the example, that helps a lot to understand, how it is intended to be done.

[boaks]

I'm some steps further.

One difference, which seems for me to be not too easy to overcome is, that some (small) parts of my module-library depends on

#include <zephyr.h> 

I searched, I read a lot, but I didn't find, what is required for the library target to add the zephyr include path.

external_lib/CMakeLists.txt that is then using a different build system. For just add the zephyr-include-path to the libraries, that seems to be a overkill.

So, is there a way to extend:

target_include_directories(tinydtls PUBLIC . aes ecc sha2)

to add the zephyr include-path?

(I guess, the next question will then be, how to pass also the zephyr compiler definitions to

target_compile_definitions(tinydtls PUBLIC ...)

)

[boaks]

target_link_libraries(tinydtls PUBLIC zephyr_interface)

Was the missing link ...

Now I need to try again to split the stuff as in yashi/module-sample.

[yashi]

Let me know if there is anything I should fix.

[boaks]

I managed to apply the pattern in yashi/module-sample to tinydtls. It compiles and can run it on the target.

@yashi thanks a lot for your great example.