Main task is to fetch external tool if one is not available in the system. It has three main modes:

• FETCH - force to fetch external tool
• FIND - force to use system tool
• AUTO - check the system, and if not available; default mode

include(find_or_fetch_package)

find_or_fetch_package(name url [VERSION version] [GIT_TAG optional_tag] [FETCH|FIND|AUTO] [EXPORT_OPTION])

• Find mode

  If FIND mode is selected, the find_package(${name} ${VERSION} QUITE) is called.

• Fetch mode

  If FETCH mode is selected, FetchContent_Declare will be called. If GIT_TAG is set, it will be used otherwise VERSION is use. If neitherGIT_TAG or VERSION is provided, will result in fatal error in FETCH|AUTO mode.

• Auto mode

  It first try to find local installation (FIND mode) and if unsuccessful, call FETCH mode.

The GIT_TAG should be provied if the VERSION cannot be used as a tag name, or another branch or commit hash is required.

The macro will register option with name ${PROJECT_NAME}_BUILTIN_${upper_case_name} (upper case of name) which can be controlled from command line, e.g.

If variable USE_BUILTIN_xxx (where xxx is the capitalized name) is set, it has priority over macro call modes. This variable should take value of the these three modes: FETCH, FIND or AUTO, e.g.:

cmake -DUSE_BUILTIN_xxx=FETCH

If EXPORT_OPTION is used it creates CACHE entry of USE_BUILTIN_xxx.

shared_or_static(name)

Creates variable ${name}_LIBRARY_TYPE being either STATIC or SHARED which values depends on combination of BUILD_SHARED_LIBS and ${name}_BUILD_SHARED.

• If neither of them is set, then name_LIBRARY_TYPE is undefined
• If only BUILD_SHARED_LIBS is set, ${name}_LIBRARY_TYPE = BUILD_SHARED_LIBS ? SHARED : STATIC
• Otherwise ${name}_LIBRARY_TYPE = ${name}_BUILD_SHARED ? SHARED : STATIC

1. Build type controlled via options

include(shared_or_static)

option(BUILD_SHARED_LIBS "Global option" OFF)
option(MyLibBuildType_BUILD_SHARED "Specific option" OFF)

shared_or_static(MyLibBuildType)

add_library(MyLib ${MyLibBuildType}_LIBRARY_TYPE source.cxx)

1. Build type hardcoded

include(shared_or_static)

set(BUILD_SHARED_LIBS ON)
set(MyLibBuildType_BUILD_SHARED OFF)

shared_or_static(MyLibBuildType)

add_library(MyLib ${MyLibBuildType}_LIBRARY_TYPE source.cxx) # MyLib is STATIC