[CMake] Setting the installation order of a script

[David Cole]

On Fri, Jul 15, 2011 at 10:55 AM, Michael Hertling <mhertling at online.de> wrote:
> On 07/14/2011 02:34 PM, David Cole wrote:
>> The only way to guarantee that your install SCRIPT and CODE segments
>> run last is to put them in their own subdirectory, and add it last.
>>
>> i.e. :
>> dir3/CMakeLists.txt:
>> INSTALL (SCRIPT setpermissions.cmake)
>>
>> CMakeLists.txt:
>> ADD_SUBDIRECTORY(dir1)
>> ADD_SUBDIRECTORY(dir2)
>> # last, so it's install rules run after all other install rules
>> ADD_SUBDIRECTORY(dir3)
>
> If I understand correctly, this is exactly what's *not* guaranteed:
>
> "Rules specified by calls to this command within a source directory are
> executed in order during installation. The order across directories is
> not defined." (documentation of INSTALL() command)
>
> Perhaps, the CMake manual could be clarified in this regard since the
> INSTALL() commands' order of execution is sometimes quite important.
>
> Regards,
>
> Michael
>
>> On Thu, Jul 14, 2011 at 4:51 AM, Mathias Tausig
>> <mathias.tausig at a-cert.at> wrote:
>>> Hy!
>>>
>>> My CMakeLists.txt in the top directory looks like this:
>>>
>>> ADD_SUBDIRECTORY(dir1)
>>> ADD_SUBDIRECTORY(dir2)
>>> INSTALL (SCRIPT setpermissions.cmake)
>>>
>>> setpermissions.cmake changes some file-owner permissions of the stuff
>>> that has been installed from dir1 and dir2. The problem is: if I execute
>>> "make install", setpermissions is run previous to the installation from
>>> the subdirectories.
>>> Is there some way to make the script from the last line wait, until
>>> everything else has been installed?
>>> I am using cmake-2.8.3 under linux.
>>>
>>> cheer
>>> Mathias
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Given that add_subdirectory calls are processed in order, and that
install rules within a directory are processed in order within that
directory, it follows that:

Given:
add_subdirectory(dir1)
add_subdirectory(dir2)
add_subdirectory(dir3)

Yields install rules running in the predictable order that you'd expect.

However, what most don't expect, and what is actually true, is that
interleaving install calls and add_subdirectory calls do not yield the
same interleaving in the generated install files. Hence, you cannot
simply do an install(SCRIPT at the bottom of your main CMakeLists file
and have it run after all the install rules from all the previous
sub-directories. That's unexpected to most. Which leads to the "not
defined" documentation you've pointed out. By leaving it undefined,
we're reserving the right to *try* to possibly re-factor/re-arrange it
in the future, perhaps changing it and defining it later.

Practically speaking, I don't give that a very good chance, because
many projects out there are already relying on some portions of the
existing actual, in practice behavior despite the fact that it's
undefined.

What I'm saying here is: I've done this myself in some projects, and
know that it works, and don't expect it to change in the near future.
Despite the "not defined" blurb in the docs.


Cheers,
David C.