qiBuild CMake framework design

General design decisions

qiBuild CMake framework is designed around a few principles:

  • Staying close to the standards
  • Trying to follow CMake best practices (from CMake wiki or in /usr/share/cmake-2.8/Modules/readme.txt)
  • Do not get into the developer’s way
  • Play nice with other build frameworks:
    • Every custom CMake function is prefixed with qi_
    • Every custom CMake files is in a qibuild subidrectory
    • Generated CMake code is always pure, standard CMake code
    • Absolutely NO environment variable is required, except for PATH and PYTHONPATH

qiBuild CMake Concepts

SDK
A directory containing files used to compile other code. A SDK always has a layout, following POSIX and cmake conventions.

Here is an example of a SDK containing the bar executable, a bar.cfg configuration file for bar, a foo library with the foo-config.cmake file, and the foo.h hader:

  <sdk>
  |__ include
      |__ foo
           |__ foo.h
  |__ lib
      |__  libfoo.a
      |__  libfoo.a
      |__  foo.lib
  |__ bin
      |__ bar
      |__ foo.dll
      |__ bar.exe
  |__ cmake
      |__ foo
          |__ foo-config.cmake
  |__ etc
         |__ bar
             |__ bar.cfg


The root of a SDK can safely be added to ``CMAKE_FIND_ROOT_PATH``
variable.
package

A package is simply an archive containing the one or several SDKs. If always has a .tar.gz extension on UNIX, and a .zip extension on windows.

All files are in the same top dir, so it is safe to extract it everywhere.

Some packages may also need a toolchain file.

toolchain file
Usually, your are supposed to use a toolchain file when cross-compiling with CMake, with the CMAKE_TOOLCHAIN_FILE variable.

For qiBuild, we extend the usage of the toolchain file a little bit.

In a toolchain file, you may:

  • Force a compiler (which is the main purpose of a toolchain file)
  • Set some CMake flags (for instance CMAKE_OSX_ARCHITECTURES)
  • Or set some CMake variables like CMAKE_FIND_ROOT_PATH

A package can be associated to a toolchain file.

For instance, you may have a simple package foobar containing the result of the installation of the bar executable and the foo libaray, requiring now toolchain file at all, or a complex package name geode-ctc containg some libs in ctc/sysroot/usr/lib, and a cross-compiler in ctc/cross, and a toolchain file forcing the compiler to be ctc/cross/bin/gcc, and setting CMAKE_FIND_ROOT_PATH to ctc/sysroot.

toolchain
A toolchain is simply a collection of packages

Overviews

You can read the following sections if you want to understand deeply how qibuild works, under the hood.

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