Allow usage as submodule #29

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1. tcbrindle commented on Jan 20, 2020

   

   tcbrindle

   on Jan 20, 2020

   Owner

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   This sounds like a good idea. I'm not a CMake expert though -- I know how to make an "interface library", but how do I do the namespacing bit?
2. Flamefire commented on Jan 21, 2020

   

   Flamefire

   on Jan 21, 2020

   Author

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   You use an ALIAS library: add_library(tcb::span ALIAS tcb_span) where `tcb_span is your regular INTERFACE library. And while you are at it: You can also add installation support:

   include(GNUInstallDirs)
   include(CMakePackageConfigHelpers)
     target_include_directories(tcb_span INTERFACE $<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>)
   
     install(TARGETS tcb_span
       EXPORT ${PROJECT_NAME}Targets
     )
     install(DIRECTORY include/ DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
     set(configFile ${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}Config.cmake)
     set(versionFile ${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}ConfigVersion.cmake)
     set(configInstallDestination lib/cmake/${configFolder})
   
     configure_package_config_file(
       ${PROJECT_SOURCE_DIR}/Config.cmake.in
       ${configFile} 
       INSTALL_DESTINATION ${configInstallDestination}
     )
     write_basic_package_version_file(
       ${versionFile}
       COMPATIBILITY SameMajorVersion
     )
   
     install(FILES ${configFile} ${versionFile} DESTINATION ${configInstallDestination})
   
     install(
       EXPORT ${PROJECT_NAME}Targets
       NAMESPACE "tcb::"
       DESTINATION ${configInstallDestination}
     )
   

   This is mostly C&P from another project so double-check. You'll need to use a suitable project name (with the above users will be able to do find_package(<project-name>)) and use the VERSION x.y.z argument for project. The referenced Config.cmake.in is simple:

   @PACKAGE_INIT@
   
   include("${CMAKE_CURRENT_LIST_DIR}/@PROJECT_NAME@Targets.cmake")
   

   And yes it is a shame that so much boilerplate is required in CMake...

   If you got any questions, feel free to ask. I can also review a PR