if(variable)
    # If variable is `ON`, `YES`, `TRUE`, `Y`, or non zero number
else()
    # If variable is `0`, `OFF`, `NO`, `FALSE`, `N`, `IGNORE`, `NOTFOUND`, `""`, or ends in `-NOTFOUND`
endif()
# If variable does not expand to one of the above, CMake will expand it then try again

target_compile_options(MyTarget PRIVATE "$<$<CONFIG:Debug>:--my-flag>")

target_include_directories(
    MyTarget
  PUBLIC
    $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
    $<INSTALL_INTERFACE:include>
)

function(SIMPLE REQUIRED_ARG)
    message(STATUS "Simple arguments: ${REQUIRED_ARG}, followed by ${ARGN}")
    set(${REQUIRED_ARG} "From SIMPLE" PARENT_SCOPE)
endfunction()
simple(This Foo Bar)
message("Output: ${This}")

#pragma once
#define MY_VERSION_MAJOR @PROJECT_VERSION_MAJOR@
#define MY_VERSION_MINOR @PROJECT_VERSION_MINOR@
#define MY_VERSION_PATCH @PROJECT_VERSION_PATCH@
#define MY_VERSION_TWEAK @PROJECT_VERSION_TWEAK@
#define MY_VERSION "@PROJECT_VERSION@"

configure_file (
    "${PROJECT_SOURCE_DIR}/include/My/Version.h.in"
    "${PROJECT_BINARY_DIR}/include/My/Version.h"

# Assuming the canonical version is listed in a single line
# This would be in several parts if picking up from MAJOR, MINOR, etc.
set(VERSION_REGEX "#define MY_VERSION[ \t]+\"(.+)\"")
# Read in the line containing the version
file(STRINGS "${CMAKE_CURRENT_SOURCE_DIR}/include/My/Version.hpp"
VERSION_STRING REGEX ${VERSION_REGEX})
# Pick out just the version
string(REGEX REPLACE ${VERSION_REGEX} "\\1" VERSION_STRING "${VERSION_STRING}")
# Automatically getting PROJECT_VERSION_MAJOR, My_VERSION_MAJOR, etc.
project(My LANGUAGES CXX VERSION ${VERSION_STRING})

- project
- .gitignore
- README.md
- LICENCE.md
- CMakeLists.txt
- cmake
- FindSomeLib.cmake
- something_else.cmake
- include
- project
- lib.hpp
- src
- CMakeLists.txt
- lib.cpp
- apps
- CMakeLists.txt
- app.cpp
- tests
- CMakeLists.txt
- testlib.cpp
- docs
- CMakeLists.txt
- extern
- googletest
- scripts
- helper.py

set(CMAKE_MODULE_PATH "${PROJECT_SOURCE_DIR}/cmake" ${CMAKE_MODULE_PATH})

find_package(Git QUIET)
if(GIT_FOUND AND EXISTS "${PROJECT_SOURCE_DIR}/.git")
execute_process(COMMAND ${GIT_EXECUTABLE} submodule update --init --recursive
WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
RESULT_VARIABLE GIT_SUBMOD_RESULT)
if(NOT GIT_SUBMOD_RESULT EQUAL "0")
message(FATAL_ERROR "git submodule update --init --recursive failed with ${GIT_SUBMOD_RESULT}, please checkout submodules")
endif()
endif()

find_package(PythonInterp REQUIRED)
add_custom_command(OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/include/Generated.hpp"
COMMAND "${PYTHON_EXECUTABLE}" "${CMAKE_CURRENT_SOURCE_DIR}/scripts/GenerateHeader.py" --argument
DEPENDS some_target)
add_custom_target(generate_header ALL
DEPENDS "${CMAKE_CURRENT_BINARY_DIR}/include/Generated.hpp")
install(FILES ${CMAKE_CURRENT_BINARY_DIR}/include/Generated.hpp DESTINATION  include)

# Almost all CMake files should start with this
# You should always specify a range with the newest
# and oldest tested versions of CMake. This will ensure
# you pick up the best policies.
cmake_minimum_required(VERSION 3.1...3.22)
# This is your project statement. You should always list languages;
# Listing the version is nice here since it sets lots of useful variables
project(
ModernCMakeExample
VERSION 1.0
LANGUAGES CXX)
# If you set any CMAKE_ variables, that can go here.
# (But usually don't do this, except maybe for C++ standard)
# Find packages go here.
# You should usually split this into folders, but this is a simple example
# This is a "default" library, and will match the *** variable setting.
# Other common choices are STATIC, SHARED, and MODULE
# Including header files here helps IDEs but is not required.
# Output libname matches target name, with the usual extensions on your system
add_library(MyLibExample simple_lib.cpp simple_lib.hpp)
# Link each target with other targets or add options, etc.
# Adding something we can run - Output name matches target name
add_executable(MyExample simple_example.cpp)
# Make sure you link your targets with this command. It can also link libraries and
# even flags, so linking a target that does not exist will not give a configure-time error.
target_link_libraries(MyExample PRIVATE MyLibExample)

set_target_properties(myTarget PROPERTIES
CXX_STANDARD 11
CXX_STANDARD_REQUIRED YES
CXX_EXTENSIONS NO
)

set(CMAKE_POSITION_INDEPENDENT_CODE ON)

find_program(CCACHE_PROGRAM ccache)
if(CCACHE_PROGRAM)
set(CMAKE_CXX_COMPILER_LAUNCHER "${CCACHE_PROGRAM}")
set(CMAKE_CUDA_COMPILER_LAUNCHER "${CCACHE_PROGRAM}") # CMake 3.9+
endif()

~/package # cmake -S . -B build-tidy -DCMAKE_CXX_CLANG_TIDY="$(which clang-tidy);-fix"

message(STATUS "MY_VARIABLE=${MY_VARIABLE}")

include(CMakePrintHelpers)
cmake_print_variables(MY_VARIABLE)

cmake_print_properties(
TARGETS my_target
PROPERTIES POSITION_INDEPENDENT_CODE
)

cmake -S . -B build --trace-source=CMakeLists.txt

add_test(
NAME
ExampleCMakeBuild
COMMAND
"${CMAKE_CTEST_COMMAND}"
--build-and-test "${My_SOURCE_DIR}/examples/simple"
"${CMAKE_CURRENT_BINARY_DIR}/simple"
--build-generator "${CMAKE_GENERATOR}"
--test-command "${CMAKE_CTEST_COMMAND}"