CMake实践(3)

一,本期目标

[sun@localhost t3]$ cat README
t3:静态库(.a)与动态库(.so)构建
    任务:1,建立一个静态库和动态库,提供HelloFunc函数供其他程序编程使用
             HelloFunc向终端输出Hello World字符串
          2,安装头文件与共享库
使用方法
到<path_to>/t3/build,执行:
cmake -DCMAKE_INSTALL_PREFIX=/home/TOM/tmp ..
make
make instal

二,目录结构:

[sun@localhost t3]$ tree ../t3/
../t3
├── build
├── CMakeLists.txt
├── lib
│   ├── CMakeLists.txt
│   ├── hello.cpp
│   └── hello.h
└── README

三,CMakeList.txt

[sun@localhost t3]$ cat CMakeLists.txt

PROJECT(HELLOLIB)
cmake_minimum_required(VERSION 2.6)
ADD_SUBDIRECTORY(lib)
[sun@localhost t3]$ cat lib/CMakeLists.txt
SET(LIBHELLO_SRC hello.cpp)

#1)注意: 下面2句不能同时出现,因为target名称是唯一的,如果想要得到相同名称的动态库和静态库
#必须借助于SET_TARGET_PROPERTIES
ADD_LIBRARY(hello SHARED ${LIBHELLO_SRC})
#ADD_LIBRARY(hello STATIC ${LIBHELLO_SRC})

#2)注意:有了以下两句,我们就可以同时得到同名的动态库和静态库了,
#      但是你会发现libhello.so却消失了,因为cmake在构建一个新的target时,
#      会尝试清理掉其它使用这个名字的库,所以在构建libhello.a时,就会清理掉libhello.so
ADD_LIBRARY(hello_static STATIC ${LIBHELLO_SRC})
SET_TARGET_PROPERTIES(hello_static PROPERTIES OUTPUT_NAME "hello")

#3)要避免同名不同类型的库覆盖,需要再借助于SET_TARGET_PROPERTIES指令
SET_TARGET_PROPERTIES(hello PROPERTIES CLEAN_DIRECT_OUTPUT 1)
SET_TARGET_PROPERTIES(hello_static PROPERTIES CLEAN_DIRECT_OUTPUT 1)

#4)增加动态库版本号
#   按照规则,动态库是应该包含一个版本号的,我们看一下系统的动态库,一般情况是:
#   libhello.so.1.2
#   libhello.so->libhello.so.1
#   libhello.so.1->libhello.so.1.2
#   以下命令中,VERSION指代动态库版本,SOVERSION指代API版本
SET_TARGET_PROPERTIES(hello PROPERTIES VERSION 1.2 SOVERSION 1)

#5)安装共享库和头文件
#   hello的共享库安装到<prefix>/lib目录
#   hello.h安装到<prefix>/include/hello目录
INSTALL(TARGETS hello hello_static
        LIBRARY DESTINATION lib
        ARCHIVE DESTINATION lib)

INSTALL(FILES hello.h DESTINATION include/hello)

#COMMAND: ADD_LIBRARY(libname [SHARED|STATIC|MODULE] [EXECLUDE FROM_ALL]
#             source1 source2 ... sourceN)
#注意:不需要写全libhello.so,只需要填写hello即可,cmake系统会自动为你生成libhello.X
#       类型有3种:SHARED(动态库),
#                  STATIC(静态库),
#                  MODULE(在使用dyld的系统有效,否则被当作SHARED对待)
#       EXCLUDE_FROM_ALL:这个库不会被默认构建,除非有其它的组件依赖或者手工构建

#COMMAND: SET_TARGET_PROPERTIES(target1 target2 ...
#                               PROPERTIES prop1 value1 prop2 value2 ...)
#定义:用来设置输出的名称,对于动态库,还可以用来指定动态库版本和API版本。
#备注:其它对应的指令是:GET_TARGET_PROPERTIES(VAR target property)
#      如:GET_TARGET_PROPERTY(OUTPUT_VALUE hello_static OUTPUT_NAME)
#          MESSAGE(STATUS "This is the hello_static OUTPUT_NAME:"${OUTPUT_VALUE})
#          如果没有这个属性定义,则返回NOTFOUND

四,运行结果

[sun@localhost t3]$ cd build/
[sun@localhost build]$ cmake ..
-- The C compiler identification is GNU
-- The CXX compiler identification is GNU
-- Check for working C compiler: /opt/gcc/bin/gcc
-- Check for working C compiler: /opt/gcc/bin/gcc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working CXX compiler: /opt/gcc/bin/c++
-- Check for working CXX compiler: /opt/gcc/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Configuring done
-- Generating done
-- Build files have been written to: /home/sun/program/cmake_practice/t3/build
[sun@localhost build]$ make
Scanning dependencies of target hello
[ 50%] Building CXX object lib/CMakeFiles/hello.dir/hello.cpp.o
Linking CXX shared library libhello.so
[ 50%] Built target hello
Scanning dependencies of target hello_static
[100%] Building CXX object lib/CMakeFiles/hello_static.dir/hello.cpp.o
Linking CXX static library libhello.a
[100%] Built target hello_static

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