cmake for python projects (was: KDE/kdegames)

Wolfgang Rohdewald wolfgang at rohdewald.de
Sun Sep 26 19:06:29 BST 2010


(redirecting from kde-game-devel to kde-core-devel)

On Sonntag 26 September 2010, Alexander Neundorf wrote:
> On Sunday 26 September 2010, Wolfgang Rohdewald wrote:
> > There should be clear guidelines defined for python
> > projects somewhere in the wiki IMHO. I am not a cmake
> > export nor a packager and would really prefer to stay
> > out of this discussion. Anyway I would volunteer to
> > write up a new small chapter "CMake and Python projects"
> > at http://techbase.kde.org/Development/CMake
> > if nobody else does.
> 
> This would be really *great*.
> I can help with any cmake issues, but I'm no python expert.
> Just start it, I'll give comments :-)

Before starting, I do have a fundamental question about cmake
and python:

Who uses cmake? Only the distribution packagers?
Or also developers?
Or even end users?

I can see only one switch in kajongg/CMakeLists.txt:
IF(INSTALL_KAJONGG)

if that is set, both make (aka compiling) and make install
(aka installing) do something in the build directory.
If it is not set, both do nothing.

but if cmake cannot distinguish between dependencies for
compiling and for installing, I do not see how all of
the three user groups can get satisfying results.

I do not think developers are a problem. If kajongg cannot
import needed modules at execution time, they will get
an error message and know what to do. Kajongg will even
tell them what they need to install in a nice KDialog
(although that is rather unpythonic, citing Sebastian
K├╝gler on kde-core-devel)

If an end user uses cmake for installation, I would expect
the same from her.

So only packagers are of concern. And they do not care
about dependencies if they do not need them for compiling,
they might even patch them out for simplifying and 
speeding up their build system (as stated by Sune Vuorela
and Johannes Obermeyer, distribution packagers 
for Debian and Suse).

So kajongg/CMakeLists.txt and kdegames/CMakeLists.txt
should not enforce runtime dependencies and probably
not even check for them at all.

Am I right so far? And if yes, how do packagers ensure
correct install dependencies for their packages? By
testing kajongg or by believing what the authors tell
them informally? Or should there be a required file
like "kajongg/RuntimeDepencencies" for python projects?

-- 
Wolfgang



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