| --- |
| short-description: Overview of the Meson build system |
| ... |
| |
| # Overview |
| |
| Meson is a build system that is designed to be as user-friendly as |
| possible without sacrificing performance. The main tool for this is a |
| custom language that the user uses to describe the structure of his |
| build. The main design goals of this language has been simplicity, |
| clarity and conciseness. Much inspiration was drawn from the Python |
| programming language, which is considered very readable, even to |
| people who have not programmed in Python before. |
| |
| Another main idea has been to provide first class support for modern |
| programming tools and best practices. These include features as varied |
| as unit testing, code coverage reporting, precompiled headers and the |
| like. All of these features should be immediately available to any |
| project using Meson. The user should not need to hunt for third party |
| macros or write shell scripts to get these features. They should just |
| work out of the box. |
| |
| This power should not come at the expense of limited usability. Many |
| software builds require unorthodox steps. A common example is that you |
| first need to build a custom tool and then use that tool to generate |
| more source code to build. This functionality needs to be supported |
| and be as easy to use as other parts of the system. |
| |
| Terminology |
| -- |
| |
| Meson follows the overall structure of other popular build systems, |
| such as CMake and GNU Autotools. This means that the build is divided |
| into two discrete steps: *configure step* and *build step*. The first |
| step inspects the system, checks for dependencies and does all other |
| steps necessary to configure the build. It then generates the actual |
| build system. The second step is simply executing this generated build |
| system. The end result is a bunch of *build targets*, which are |
| usually executables and shared and static libraries. |
| |
| The directory that contains the source code is called the *source |
| directory*. Correspondingly the directory where the output is written |
| is called the *build directory*. In other build systems it is common |
| to have these two be the same directory. This is called an *in-source |
| build*. The case where the build directory is separate is called an |
| *out-of-source build*. |
| |
| What sets Meson apart from most build systems is that it enforces a |
| separate build directory. All files created by the build system are |
| put in the build directory. It is actually impossible to do an |
| in-source build. For people used to building inside their source tree, |
| this may seem like a needless complication. However there are several |
| benefits to doing only out-of-source builds. These will be explained |
| in the next chapter. |
| |
| When the source code is built, a set of *unit tests* is usually |
| run. They ensure that the program is working as it should. If it does, |
| the build result can be *installed* after which it is ready for use. |
