# CMake Commands

## CMake Commands

Starting from v3.0, CMake commands are all in lower case SET() --> set()

#### Common

* `message([<mode>] "message to display" ...)`
* `set(<variable> <value> [[CACHE <type> <docstring> [FORCE]] | PARENT_SCOPE])`
* `unset(<variable> [CACHE | PARENT_SCOPE])`
* `option(<option_variable> "help string describing option" [initial value])`
* `export(EXPORT <export-name> [NAMESPACE <namespace>] [FILE <filename>])`
* `install(TARGETS targets... [EXPORT <export-name>] [...])`
* `file(WRITE filename "message to write"... )` also READ/APPEND/...
* `list(APPEND <list> [<element> ...])` also LENGTH/FIND/INSERT/REMOVE/SORT...
* `string(REGEX REPLACE <regular_expression> <replace_expression> <output variable>` `<input> [<input>...])`also FIND/COMPARE/LENGTH/TOLOWER...

```bash
message("words to user")
message(STATUS ${PROJECT_SOURCE_DIR})  # may be ignored by catkin build
# mode: (none), STATUS, WARNING, AUTHOR_WARNING, SEND_ERROR, FATAL_ERROR, DEPRECATION

set(CMAKE_BUILD_TYPE Release)  # Debug RelWithDebInfo MinSizeRel
set(LIBRARY_OUTPUT_PATH ${PROJECT_BINARY_DIR}/lib)

unset(ENV{LD_LIBRARY_PATH}) # <variable> can be an environment variable

option(BUILD_DOC "Build documentation" ON) 
# can be overwritten by "cmake -DBUILD_DOC=OFF .."

export(TARGETS ${TEASERPP_EXPORTED_TARGETS} FILE teaserpp-exports.cmake)

install(FILES cmake/teaserppConfig.cmake
        DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/teaserpp)

file(STRINGS myfile.txt myfile)
# stores a list in the variable “myfile” 
# in which each item is a line from the input file.

list(APPEND CMAKE_MODULE_PATH ${PROJECT_SOURCE_DIR}/cmake)

string(REGEX REPLACE "/$" "" CMAKE_INSTALL_PREFIX "${CMAKE_INSTALL_PREFIX}")
```

#### Flow Control

* `if()`, `elseif()`, `else()`, `endif()`
* `while()`, `endwhile()`
* `foreach()`, `endforeach()`
* `macro()`, `endmacro()`
* `function()`, `endfunction()`
* `break()`, `return()`
* `enable_language(<lang> [OPTIONAL] )`
* `enable_testing()`

#### Build Target

* `find_file (<VAR> name1 [path1 path2 ...])`
* `find_library (<VAR> name1 [path1 path2 ...])`
* `find_package(<package> [version] [EXACT] [QUIET] [MODULE] [REQUIRED] [[COMPONENTS]` `[components...]] [OPTIONAL_COMPONENTS components...] [NO_POLICY_SCOPE])`
* `find_path (<VAR> name1 [path1 path2 ...])`
* `find_program (<VAR> name1 [path1 path2 ...])`
* `add_compile_options(<option> ...)`
* `add_definitions(-DFOO -DBAR ...)`: Adds -D define flags to the compilation of source files.
* `add_dependencies(<target> [<target-dependency>]...)`
* `add_executable(<name> source1 [source2 ...])`
* `add_library(<name> [STATIC | SHARED | MODULE] source1 [source2 ...])`
* `add_subdirectory()`
* `add_test()`
* `include_directories()` for all build targets
* `target_include_directories()` for a specific build target
* `target_link_libraries()` link to a specific target
  * Header-only libraries (e.g., Eigen3) are not needed to be linked here.
  * `target_link_directories()` is not encouraged to use

#### Build Dependencies

* `configure_file(<input> <output> [...])` Copy a file to another location and modify its contents.
* `execute_process(COMMAND <cmd1> [args1...]] [WORKING_DIRECTORY <directory>] [...])`&#x20;
* `include(<file|module>[...])` Load and run CMake code from a file or module.

```bash
cmake_minimum_required(VERSION 3.10)

project(tinyply-download NONE)

include(ExternalProject)
ExternalProject_Add(pmc
        GIT_REPOSITORY    https://github.com/jingnanshi/tinyply.git
        GIT_TAG           0b9fff8e8bd4d37256554fe40cf76b2f3134377b
        SOURCE_DIR        "${CMAKE_CURRENT_BINARY_DIR}/tinyply-src"
        BINARY_DIR        "${CMAKE_CURRENT_BINARY_DIR}/tinyply-build"
        CONFIGURE_COMMAND ""
        BUILD_COMMAND     ""
        INSTALL_COMMAND   ""
        TEST_COMMAND      ""
        )
```