[CMake] How do you handle recursive dependencies in CMake

[Sven Baars]

Hi Ray,

The packages I use are installed in a non-standard path, because I don't
have access to the system directories on most systems I work on, but are
used by many other libraries. They are also all separate packages, not
packages in the same source tree. I did not see my attachment on the
mailing list archive, so instead I just put it on Github. It can be
found here:

https://github.com/Sbte/cmake-example

I hope the example shows my workflow, and also what doesn't work for me.

Sven

On 06/28/2016 11:52 AM, Raymond Wan wrote:
> Hi Sven,
>
>
> On Tue, Jun 28, 2016 at 5:26 PM, Sven Baars <s.baars at rug.nl> wrote:
>> Hey all,
>>
>> Since I did not receive a reply to my previous mail, I decided to write a
>> minimal example explaining my problem, where I kept al the names as I used
>> in my previous mails. I hope that after seeing my example, someone can
>> explain me what I am doing wrong here. I included a script that reproduces
>> the problem.
>>
>> Cheers,
>> Sven
>
> I'm not much of an expert with CMake, but I can explain to you what
> I've done, at least.
>
> If I understand correctly, package X makes use of package Y, but
> during compilation, it cannot find it?  I think what you can do
> depends on whether X and Y are in two separate source trees.
>
> If they are, then it is almost like Y is the zlib library.  Then what
> you can do is, like the zlib library, install it into a system
> directory (i.e., via INSTALL ()) and then X will use a FIND_PACKAGE to
> look for it.
>
> But, suppose Y isn't like zlib.  For example, it is a library that is
> within the same source tree and will only ever be used by X (both of
> which are written by you).  I think this is the scenario that you're
> talking about?  In my case, I have done this in my CMakeLists.txt:
>
> SET (CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR})
>
> I guess you can set it
> [https://cmake.org/cmake/help/v3.3/variable/CMAKE_LIBRARY_OUTPUT_DIRECTORY.html]
> to anything so that all of the libraries will be installed into one
> place without doing an INSTALL.  Of course, this directory is or
> somewhere within the build/ directory.  (I suppose doing an install
> into ${CMAKE_BINARY_DIR} would achieve the same thing?)
>
> I had previously installed Y's archive into a system directory, but
> besides the need to run FIND_PACKAGE, I thought it was "silly" to
> install an archive into a system directory that is only used by my own
> program.  Seems a bit messy and intrusive to the end-user -- my
> libraries are quite unlike zlib; few chance someone else will use it
> :-) .  At the very least, this approach keeps it in one place within
> build/ .
>
> I'm not sure if it is the "right" way to do it, but this is what I do
> at the moment...  I hope it helps!
>
> Ray