zstd/build/cmake/README.md

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# Cmake contributions
Contributions to the cmake build configurations are welcome. Please
use case sensitivity that matches modern (ie. cmake version 2.6 and above)
conventions of using lower-case for commands, and upper-case for
variables.
## How to build
As cmake doesn't support command like `cmake clean`, it's recommended to perform a "out of source build".
To do this, you can create a new directory and build in it:
```sh
cd build/cmake
mkdir builddir
cd builddir
cmake ..
make
```
Then you can clean all cmake caches by simply delete the new directory:
```sh
rm -rf build/cmake/builddir
```
And of course, you can directly build in build/cmake:
```sh
cd build/cmake
cmake
make
```
To show cmake build options, you can:
```sh
cd build/cmake/builddir
cmake -LH ..
```
Bool options can be set to `ON/OFF` with `-D[option]=[ON/OFF]`. You can configure cmake options like this:
```sh
cd build/cmake/builddir
cmake -DZSTD_BUILD_TESTS=ON -DZSTD_LEGACY_SUPPORT=ON ..
make
```
### referring
[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)
## CMake Style Recommendations
### Indent all code correctly, i.e. the body of
* if/else/endif
* foreach/endforeach
* while/endwhile
* macro/endmacro
* function/endfunction
Use spaces for indenting, 2, 3 or 4 spaces preferably. Use the same amount of
spaces for indenting as is used in the rest of the file. Do not use tabs.
### Upper/lower casing
Most important: use consistent upper- or lowercasing within one file !
In general, the all-lowercase style is preferred.
So, this is recommended:
```
add_executable(foo foo.c)
```
These forms are discouraged
```
ADD_EXECUTABLE(bar bar.c)
Add_Executable(hello hello.c)
aDd_ExEcUtAbLe(blub blub.c)
```
### End commands
To make the code easier to read, use empty commands for endforeach(), endif(),
endfunction(), endmacro() and endwhile(). Also, use empty else() commands.
For example, do this:
```
if(FOOVAR)
some_command(...)
else()
another_command(...)
endif()
```
and not this:
```
if(BARVAR)
some_other_command(...)
endif(BARVAR)
```
### Other resources for best practices
https://cmake.org/cmake/help/latest/manual/cmake-developer.7.html#modules