| 1 | # Cmake contributions |
| 2 | |
| 3 | Contributions to the cmake build configurations are welcome. Please |
| 4 | use case sensitivity that matches modern (i.e. cmake version 2.6 and above) |
| 5 | conventions of using lower-case for commands, and upper-case for |
| 6 | variables. |
| 7 | |
| 8 | ## How to build |
| 9 | |
| 10 | As cmake doesn't support command like `cmake clean`, it's recommended to perform an "out of source build". |
| 11 | To do this, you can create a new directory and build in it: |
| 12 | ```sh |
| 13 | cd build/cmake |
| 14 | mkdir builddir |
| 15 | cd builddir |
| 16 | cmake .. |
| 17 | make |
| 18 | ``` |
| 19 | Then you can clean all cmake caches by simply delete the new directory: |
| 20 | ```sh |
| 21 | rm -rf build/cmake/builddir |
| 22 | ``` |
| 23 | |
| 24 | And of course, you can directly build in build/cmake: |
| 25 | ```sh |
| 26 | cd build/cmake |
| 27 | cmake |
| 28 | make |
| 29 | ``` |
| 30 | |
| 31 | To show cmake build options, you can: |
| 32 | ```sh |
| 33 | cd build/cmake/builddir |
| 34 | cmake -LH .. |
| 35 | ``` |
| 36 | |
| 37 | Bool options can be set to `ON/OFF` with `-D[option]=[ON/OFF]`. You can configure cmake options like this: |
| 38 | ```sh |
| 39 | cd build/cmake/builddir |
| 40 | cmake -DZSTD_BUILD_TESTS=ON -DZSTD_LEGACY_SUPPORT=OFF .. |
| 41 | make |
| 42 | ``` |
| 43 | |
| 44 | ### referring |
| 45 | [Looking for a 'cmake clean' command to clear up CMake output](https://stackoverflow.com/questions/9680420/looking-for-a-cmake-clean-command-to-clear-up-cmake-output) |
| 46 | |
| 47 | ## CMake Style Recommendations |
| 48 | |
| 49 | ### Indent all code correctly, i.e. the body of |
| 50 | |
| 51 | * if/else/endif |
| 52 | * foreach/endforeach |
| 53 | * while/endwhile |
| 54 | * macro/endmacro |
| 55 | * function/endfunction |
| 56 | |
| 57 | Use spaces for indenting, 2, 3 or 4 spaces preferably. Use the same amount of |
| 58 | spaces for indenting as is used in the rest of the file. Do not use tabs. |
| 59 | |
| 60 | ### Upper/lower casing |
| 61 | |
| 62 | Most important: use consistent upper- or lowercasing within one file ! |
| 63 | |
| 64 | In general, the all-lowercase style is preferred. |
| 65 | |
| 66 | So, this is recommended: |
| 67 | |
| 68 | ``` |
| 69 | add_executable(foo foo.c) |
| 70 | ``` |
| 71 | |
| 72 | These forms are discouraged |
| 73 | |
| 74 | ``` |
| 75 | ADD_EXECUTABLE(bar bar.c) |
| 76 | Add_Executable(hello hello.c) |
| 77 | aDd_ExEcUtAbLe(blub blub.c) |
| 78 | ``` |
| 79 | |
| 80 | ### End commands |
| 81 | To make the code easier to read, use empty commands for endforeach(), endif(), |
| 82 | endfunction(), endmacro() and endwhile(). Also, use empty else() commands. |
| 83 | |
| 84 | For example, do this: |
| 85 | |
| 86 | ``` |
| 87 | if(FOOVAR) |
| 88 | some_command(...) |
| 89 | else() |
| 90 | another_command(...) |
| 91 | endif() |
| 92 | ``` |
| 93 | |
| 94 | and not this: |
| 95 | |
| 96 | ``` |
| 97 | if(BARVAR) |
| 98 | some_other_command(...) |
| 99 | endif(BARVAR) |
| 100 | ``` |
| 101 | |
| 102 | ### Other resources for best practices |
| 103 | |
| 104 | https://cmake.org/cmake/help/latest/manual/cmake-developer.7.html#modules |