1. Introduction to CMake, v. 2
Content:
Basic CMake usage
Ready to use samples
Advanced CMake usage
Document history:
2009 Constantine Shulyupin,
2007 Jan Engels, DESY,

2. Purposes of a build system
Efficiency: Save time on recompilations
Flexibility: Configure compilation parameters
(optimization, logging, debug and release builds)
Scalability: Manage subproject and libraries
Portability: Compile for different platforms
Introduction to CMake, v. 2

3. Introduction to CMake, v. 2
Major CMake features
Generates native build environments
UNIX/Linux -> Makefiles
Windows -> VS Projects/Workspaces
Apple -> Xcode
Eclipse projects
Big library of helper commands (Finders)
Cross-Platform (easy to port)
Introduction to CMake, v. 2

4. Introduction to CMake, v. 2
Build process
Target projects:
CMake Source file:
Makefile
CMakeLists.txt
CMakeLists.txt
CMakeLists.txt
CMake
Eclipse
Generated internal files:
KDevelop
CMakeCache.txt
MS Visual Studio
CMakeFiles/
And other
Introduction to CMake, v. 2

5. Introduction to CMake, v. 2
CMake source file
CMakeLists.txt
Input text files that contain the project parameters and describe the flow control of the build process in simple CMake language.
Introduction to CMake syntax:
# This is a comment
command(argument1 argument2 ...argumentN)
COMMAND(argument1 argument2 ...argumentN)
Introduction to CMake, v. 2

6. Introduction to CMake, v. 2
“Hello world!”
File hello.c :
int main() { printf("Hello, world!\n"); }
File CMakeLists.txt :
add_executable(hello hello.c)
Shell:
$ cmake .
$ make
$ ./hello
Hello, world!
Introduction to CMake, v. 2

7. Introduction to CMake, v. 2
Using Libraries
For C source code:
...
pthread_create(&pt, NULL, routine, NULL);
Add to CMakeLists.txt :
target_link_libraries(pthread)
Introduction to CMake, v. 2

8. Introduction to CMake, v. 2
Creating Libraries
Initial source file:
common.h
common.c
Target library file:
libcommon.so
CMakeLists.txt :
add_library (common SHARED common.c)
Introduction to CMake, v. 2

9. Woking with subdirectories
Defining subproject:
add_subdirectory(sub)
CMake adds subdirectory to dependency. Child inherits from parent
Search include files in subdirectories:
include_directories(sub)
Search libraries in subdirectories
link_directories(sub)
Introduction to CMake, v. 2

10. Additional useful commands
project (projectname [CXX] [C] [Java])
This creates the variables projectname_BINARY_DIR and projectname_SOURCE_DIR.
cmake_minimum_required (VERSION 2.6)
Set the minimum required version of cmake for a project.
add_definitions (-g)
Arguments are passed to compiler (like CFLAGS)
message (text)
Prints text
Introduction to CMake, v. 2

11. Introduction to CMake, v. 2
Most useful commands
project(name C CPP JAVA)
cmake_minimum_required(VERSION 2.6)
add_definitions(-g) # added to CFLAGS
add_library(common SHARED common.c)
add_subdirectory(sub)
include_directories(sub)
link_directories(sub)
add_executable(app app.c)
target_link_libraries(app common pthread)
message(text)
- 10 most useful functions for 90% of projects
Introduction to CMake, v. 2

12. Introduction to CMake, v. 2
Advanced facilities
Variables and lists
Variables cache
Out-of-source build
Finding libraries
Regular expressions
Flow control
Reusable code: includes and macros
Installers
Cross-compilation
Introduction to CMake, v. 2

13. Introduction to CMake, v. 2
Variables and Lists
Variables:
set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -g")
message(CMAKE_C_FLAGS: ${CMAKE_C_FLAGS})
cmake -D <var>:<type>=<value> # define variable and store in cache
Lists
set(L 1;2;3) # semi-colon is list separator
list(APPEND L a b c )
message("\${L}=" ${L})
message("\"\${L}\"=" "${L}")
Output:
${L}=123abc
"${L}"=1;2;3;a;b;c
Introduction to CMake, v. 2

14. Introduction to CMake, v. 2
CMake Cache
Created in the build tree ( CMakeCache.txt )
Contains Entries VAR:TYPE=VALUE
Populated/Updated during configuration phase
Speeds up build process
Can be initialized with cmake -C <file>
GUI can be used to change values
Introduction to CMake, v. 2

15. Introduction to CMake, v. 2
Out-of-source build
Out-of-source build used to separate build files from sources. Very useful for multi- platform development. Change to a build directory and give path to the sources as argument:
mkdir -p ../build; cd ../build
rm -f ../hello/CMakeCache.txt # cleanup after in-source build
cmake ../hello
make
Introduction to CMake, v. 2

16. Introduction to CMake, v. 2
Finding libraries
Special cmake file written for the purpose of finding a certain piece of software and to set its libraries, include files and definitions into appropriate variables so that they can be used in the build process of another project. (e.g. FindJava.cmake, FindZLIB.cmake, FindQt4.cmake)
More than 300 modules located in /usr/share/cmake-2.6/Modules/
E.g. some lines from
/usr/share/cmake-2.6/Modules/Platform/ Linux.cmake :
SET(CMAKE_SHARED_LIBRARY_CREATE_C_FLAGS "-shared")
SET(CMAKE_SHARED_LIBRARY_LINK_C_FLAGS "-rdynamic")
SET(CMAKE_SHARED_LIBRARY_RUNTIME_C_FLAG "-Wl,-rpath,")
Introduction to CMake, v. 2

17. Introduction to CMake, v. 2
Regular expressions
Warning: non Perl compatible
set (S "abc")
string (REGEX REPLACE "b.*" "BC" S ${S})
set (VER 1.2)
string (REGEX MATCHALL "([0-9]+)"
NUMS "${VER}") # NUMS is list
Introduction to CMake, v. 2

18. Introduction to CMake, v. 2
Flow control
Most useful:
if (exp)
elseif (exp2)
else ([exp])
endif ([exp])
And other:
foreach
while
Introduction to CMake, v. 2

19. Introduction to CMake, v. 2
Reusable code
include (<file|module>)
macro (<name> [arg1 [arg2 [arg3 …]]])
command1 (ARGS ...)
command2 (ARGS …)
endmacro (<name>)
function (<name> [arg1 [arg2 [arg3 …]]])
command1 (ARGS …)
command2 (ARGS ...)
endfunction (<name>)
Introduction to CMake, v. 2

20. Introduction to CMake, v. 2
Installers
Could be very simple
install (TARGETS hello DESTINATION /tmp)
Or more complex:
set(CMAKE_INSTALL_PREFIX ....)
install (TARGETS targets... [EXPORT <export- name>]
[[ARCHIVE|LIBRARY|RUNTIME|FRAMEW ORK|BUNDLE|
PRIVATE_HEADER|PUBLIC_HEADER|RES OURCE]
[DESTINATION <dir>]
[PERMISSIONS permissions...]
[CONFIGURATIONS [Debug|Release|...]]
[COMPONENT <component>]
[OPTIONAL] [NAMELINK_ONLY|NAMELINK_SKIP]
] [...])
Introduction to CMake, v. 2

21. Introduction to CMake, v. 2
Cross-compilation
arm.cmake file:
set (CMAKE_SYSTEM_NAME Linux)
set ( CMAKE_C_COMPILER /opt/arm- 2009q1/bin/arm-none-linux-gnueabi-gcc)
set ( CMAKE_CXX_COMPILER /opt/arm- 2009q1/bin/arm-none-linux-gnueabi-gcc)
set ( CMAKE_FIND_ROOT_PATH /opt/arm- 2009q1/arm-none-linux-gnueabi/)
# adjust the default behaviour of the FIND_XXX() commands:
set (CMAKE_FIND_ROOT_PATH_MODE_PROGR AM NEVER)
set (CMAKE_FIND_ROOT_PATH_MODE_LIBRAR Y ONLY)
set (CMAKE_FIND_ROOT_PATH_MODE_INCLUD E ONLY)
$ cmake - DCMAKE_TOOLCHAIN_FILE=arm.cmake
Introduction to CMake, v. 2

22. Well known CMake usages
KDE
MySQL (on Windows only)
Introduction to CMake, v. 2

23. Introduction to CMake, v. 2
Samples
Sample sources for the presentation:
KDE:
Introduction to CMake, v. 2

24. Introduction to CMake, v. 2
Further readings
Introduction to CMake, v. 2