how to improve cmake support in kdevelop/ kdevelop support in cmake

[Alexander Neundorf]

Hi,

if we want to improve the cmake-kdevelop integration, there are two things we 
can do:

1) extend the kdevelop generator in cmake so that it produces more information 
which kdevelop can use

2) implement a more or less complete cmake parser in kdevelop


With option 1) we could produce e.g. xml files which:
-easily list all targets and commands for object files
-list e.g. the include directories for each target (might this be useful for 
finding included headers, autocompletion, etc. ?)
-and more things
I think basically this would enable kdevelop to work perfectly with cmake 
builds. But it doesn't enable kdevelop to edit the cmake files.

For editing cmake files via kdevelop kdevelop would have to parse the cmake 
files. For standard cmake files this is probably not too hard. But since 
cmake features macros, conditionals, loops etc. it can get quite hard I 
think.
E.g. let's start with something simple:

Usually you specifiy an executable this way:

add_executable(hello main.cpp foo.cpp)

For KDE you use

kde4_add_executable(khello main.cpp foo.cpp)

So simple searching for add_executable() would work only in a part of the 
cases. If we start to interpret the cmake macros, we run into other problems:

E.g. it might look like:

set(mySrcs main.cpp foo.cpp)

if (PNG_FOUND)
   set(mySrcs ${mySrcs} viewpng.cpp)
endif (PNG_FOUND)

if (JPEG_FOUND)
   set(mySrcs ${mySrcs} viewjpeg.cpp)
endif (JPEG_FOUND)

kde4_add_kcfg_files(mySrcs settings.kcfg)

kde4_add_executable(kfoo ${mySrcs} )

If kdevelop would interprete everything, it would end up with:

add_executable(kfoo main.cpp foo.cpp viewpng.cpp viewjpeg.cpp 
xxx_settings.cpp)

Then it could display in a dialog that the files named above make up the 
executable kfoo.
But what if the user wants to add a file ?
Simple add it at the place where add_executable() is called ? This is not 
possible, since this happens in kde/share/apps/cmake/KDE4Macros.cmake.
Add it to kde4_add_executable() ? Not too bad. Or add it in the first set() 
command ? Probably also good.
Or should it be added only under a certain condition as it is done with the 
viewpng.cpp and viewjpeg.cpp files ? When reading the cmake files, kdevelop 
doesn't know whether FOUND_PNG and FOUND_JPEG are true or not.

How should a GUI interface for adding libraries look like ?
Usually it is done like this:

set(additionalLibs)

find_package(JPEG)
if (JPEG_FOUND)
   set(additionalLibs ${JPEG_LIBRARIES})
endif (JPEG_FOUND)

...
target_link_libraries(kfoo ...some libs... ${additionalLibs}) 

But it could also be done differently:

find_package(JPEG)
...

if (JPEG_FOUND)
   target_link_libraries(kfoo ${JPEG_LIBRARIES}) 
endif (JPEG_FOUND)

The variable for the libraries are usually named this way, but not always. For 
some packages e.g. Qt, KDE4, there are also many libraries in one package:

find_package(KDE4)

target_link_libraries(kfoo ${KDE4_KIO_LIBS} ${KDE4_KDEUI_LIBS} ... )

The GUI can't know that if the user enters ${KDE4_KDEUI_LIBS} in the link 
libraries line edit, that it has to add find_package(KDE4).

It would be possible to edit cmake files which follow a strict convenction, 
i.e. which were created by kdevelop and not manually edited by the user.

So I'm not sure that providing a conventional GUI for setting up the build 
with cmake will work good enough.
Right know the cmake files are kdevelop project files (i.e. the CMakeLists.txt 
appear in the kfoo.kdevelop.filelist file). Maybe providing a "visually 
supported" way to edit these files would be better ?
I.e.
-open the cmake file in an editor window
-provide actions/a wizard with things like:
 - look for software package
 - add condition
 - add test
 - add library/executable

which will then insert the text in the open cmake file at a place suggested by 
the user.
E.g. a dialog could appear which lists all available packages (i.e. all 
available Find*.cmake files). Then the user could select one of them and the 
find_package(JPEG) would be inserted somewhere. After that the wizard could 
show which variables are provided by this module (e.g. JPEG_FOUND, 
JPEG_INCLUDE_DIR and JPEG_LIBRARIES). Then it could ask whether to add them 
in some appropriate place in the cmake file.
What do you think ?

Bye
Alex
-- 
Work: alexander.neundorf AT jenoptik.com - http://www.jenoptik-los.de
Home: neundorf AT kde.org                - http://www.kde.org
      alex AT neundorf.net               - http://www.neundorf.net