Vala CMake

Author:	Jakob Westhoff
Version:	Draft

Overview

Vala CMake is a collection of macros for the CMake build system to allow the creation and management of projects developed using the Vala programming language or its "Genie" flavor (less tested).

Installation

To use the Vala macros in your own project you need to copy the macro files to an arbitrary folder in your projects directory and reference them in your CMakeLists.txt file.

Assuming the macros are stored under cmake/vala in your projects folder you need to add the following information to your base CMakeLists.txt:

list(APPEND CMAKE_MODULE_PATH
    ${CMAKE_SOURCE_DIR}/cmake/vala
)

After the new module path as been added you can simply include the provided modules or use the provided find routines.

Finding Vala

The find module for vala works like any other Find module in CMake. You can use it by simply calling the usual find_package function. Default parameters like REQUIRED and QUIETLY are supported.

find_package(Vala REQUIRED)

After a successful call to the find_package function the following variables will be set:

VALA_FOUND

Whether the vala compiler has been found or not

VALA_EXECUTABLE

Full path to the valac executable if it has been found

VALA_VERSION

Version number of the available valac

Precompiling Vala sources

CMake is mainly supposed to handle c or c++ based projects. Luckily every vala program is translated into plain c code using the vala compiler, followed by normal compilation of the generated c program using gcc.

The macro vala_precompile uses that fact to create c files from your .vala sources for further CMake processing.

The first parameter provided is a variable, which will be filled with a list of c files outputted by the vala compiler. This list can than be used in conjunction with functions like add_executable or others to create the necessary compile rules with CMake.

The initial variable is followed by a list of .vala files to be compiled. Please take care to add every vala file belonging to the currently compiled project or library as Vala will otherwise not be able to resolve all dependencies.

The following sections may be specified afterwards to provide certain options to the vala compiler:

PACKAGES

A list of vala packages/libraries to be used during the compile cycle. The package names are exactly the same, as they would be passed to the valac "--pkg=" option.

OPTIONS

A list of optional options to be passed to the valac executable. This can be used to pass "--thread" for example to enable multi-threading support.

DIRECTORY

Specify the directory where the output source files will be stored. If ommitted, the source files will be stored in CMAKE_CURRENT_BINARY_DIR.

CUSTOM_VAPIS

A list of custom vapi files to be included for compilation. This can be useful to include freshly created vala libraries without having to install them in the system.

GENERATE_VAPI

Pass all the needed flags to the compiler to create an internal vapi for the compiled library. The provided name will be used for this and a <provided_name>.vapi file will be created.

GENERATE_HEADER

Let the compiler generate a header file for the compiled code. There will be a header file as well as an internal header file being generated called <provided_name>.h and <provided_name>_internal.h

The following call is a simple example to the vala_precompile macro showing an example to every of the optional sections:

vala_precompile(VALA_C
    source1.vala
    source2.vala
    source3.vala
PACKAGES
    gtk+-2.0
    gio-1.0
    posix
OPTIONS
    --thread
CUSTOM_VAPIS
    some_vapi.vapi
GENERATE_VAPI
    myvapi
GENERATE_HEADER
    myheader
)

Most important is the variable VALA_C which will contain all the generated c file names after the call. The easiest way to use this information is to tell CMake to create an executable out of it.

add_executable(myexecutable ${VALA_C})

Building a debug build

In the section OPTIONS add the '-g' option. This will instruct the Vala compiler to include the Vala source code line information in the compiled binary. Add the '--save-temps' option to keep the temporary C source files.

When running cmake add '-DCMAKE_BUILD_TYPE=Debug' option. After building the program, it can then be debugged with gdb or nemiver.

Further reading

The Pdf Presenter Console , which is a vala based project of mine, makes heavy usage of the here described macros. To look at a real world example of these macros the mentioned project is the right place to take a look. The svn trunk of it can be found at:

svn://pureenergy.cc/pdf_presenter_console/trunk

Acknowledgments

Thanks go out to Florian Sowade, a fellow local PHP-Usergroupie, who helped me a lot with the initial version of this macros and always answered my mostly dumb CMake questions.