cmake 学习¶

add_custom_command 用法¶

用来定义自定义的方法, 而且有2套签名或者说触发规则

与 `add_custom_target` 配合使用, 用于生成文件¶

这种情况下，add_custom_target 续要在add_custom_command之后出现。语法

add_custom_command(OUTPUT output1 [output2 ...]
                   COMMAND command1 [ARGS] [args1...]
                   [COMMAND command2 [ARGS] [args2...] ...]
                   [MAIN_DEPENDENCY depend]
                   [DEPENDS [depends...]]
                   [BYPRODUCTS [files...]]
                   [IMPLICIT_DEPENDS <lang1> depend1
                                    [<lang2> depend2] ...]
                   [WORKING_DIRECTORY dir]
                   [COMMENT comment]
                   [DEPFILE depfile]
                   [JOB_POOL job_pool]
                   [VERBATIM] [APPEND] [USES_TERMINAL]
                   [COMMAND_EXPAND_LISTS])

类似make的语法规则

target:dependency
  command

如果dependency不存在，就去找生成依赖本身的规则，没有也生成依赖的规则，那么make会停止。

如下的例子

 cmake_minimum_required(VERSION 3.5)
 project(test)
 add_executable(${PROJECT_NAME} main.c)
 add_custom_command(OUTPUT printout 
                    COMMAND ${CMAKE_COMMAND} -E echo compile finish
                    VERBATIM
                   )
 add_custom_target(finish
                   DEPENDS printout
                   )

finish 依赖 printout, 而add_custom_command定义了printout的规则，printout即为下面的command执行的输出

所以当生成finish目标的时候会触发上面的add_custom_command

其实这种情况下，直接将add_custome_command的command写到add_custome_target中也是一样的效果

command-line-tool¶

以上add_cunstom_command的两种用法都使用了COMMAND ${CMAKE_COMMAND} -E，这是使用了cmake内置的[命令]{https://cmake.org/cmake/help/latest/manual/cmake.1.html#run-a-command-line-tool}

运用¶

例如生成protobuf的文件, 需要自定义方法

    # output files:
    FOREACH (src ${proto_srcs})
        get_filename_component(base_name ${src} NAME_WE)
        get_filename_component(path_name ${src} PATH)

        set(src "${base_name}.proto")
        set(cpp "${base_name}.pb.cc")
        set(hpp "${base_name}.pb.h")
        set(grpc_cpp "${base_name}.grpc.pb.cc")
        set(grpc_hpp "${base_name}.grpc.pb.h")

        # custom command.
        add_custom_command(
            OUTPUT ${proto_cpp_dist}/${cpp} ${proto_cpp_dist}/${hpp} ${proto_hpp_dist}/${hpp}
              ${proto_cpp_dist}/${grpc_cpp} ${proto_cpp_dist}/${grpc_hpp}
            COMMAND ${PROTOBUF_PROTOC_EXECUTABLE}
            ARGS ${OUTPUT_PATH}
              --grpc_out ${proto_cpp_dist}
              --plugin=protoc-gen-grpc=${GRPC_CPP_PLUGIN}
              ${src} 
            DEPENDS ${src}
            COMMAND ${CMAKE_COMMAND}
            ARGS -E copy_if_different ${proto_cpp_dist}/${hpp} ${proto_hpp_dist}/${hpp}
            COMMAND ${CMAKE_COMMAND}
            ARGS -E copy_if_different  ${proto_cpp_dist}/${grpc_hpp} ${proto_hpp_dist}/${grpc_hpp}
            WORKING_DIRECTORY ${path_name}
            COMMENT "${PROTOBUF_PROTOC_EXECUTABLE} --cpp_out=${proto_cpp_dist} ${src}"
            )

        LIST(APPEND output ${proto_cpp_dist}/${cpp})
    ENDFOREACH()

单独使用, 编译触发¶

这个是当项目中有add_library或者add_excutable目标时可以在编译目标文件前/链接前/编译后触发

add_custom_command(TARGET <target>
                   PRE_BUILD | PRE_LINK | POST_BUILD
                   COMMAND command1 [ARGS] [args1...]
                   [COMMAND command2 [ARGS] [args2...] ...]
                   [BYPRODUCTS [files...]]
                   [WORKING_DIRECTORY dir]
                   [COMMENT comment]
                   [VERBATIM] [USES_TERMINAL]
                   [COMMAND_EXPAND_LISTS])

cmake 学习¶

add_custom_command 用法¶

与 add_custom_target 配合使用, 用于生成文件¶

command-line-tool¶

运用¶

单独使用, 编译触发¶

cmake 逻辑表达式¶

与 `add_custom_target` 配合使用, 用于生成文件¶