如何使用cmake创建共享库? [英] How to create a shared library with cmake?
问题描述
我已经编写了一个库,该库曾经使用自写的Makefile进行编译,但是现在我想切换到cmake。树看起来像这样(我删除了所有不相关的文件):
I have written a library that I used to compile using a self-written Makefile, but now I want to switch to cmake. The tree looks like this (I removed all the irrelevant files):
.
├── include
│ ├── animation.h
│ ├── buffers.h
│ ├── ...
│ ├── vertex.h
│ └── world.h
└── src
├── animation.cpp
├── buffers.cpp
├── ...
├── vertex.cpp
└── world.cpp
所以我想做的就是将源代码编译到共享库中,然后将其与头文件一起安装。
So what I am trying to do is just to compile the source into a shared library and then install it with the header files.
我发现的大多数示例都可以用一些共享库,但绝不只是普通共享库。
如果有人可以告诉我一个使用cmake的非常简单的库,这也将很有帮助,因此我可以以此为例。
Most examples that I have found compile executables with some shared libraries but never just a plain shared library. It would also be helpful if someone could just tell me a very simple library that uses cmake, so I can use this as an example.
推荐答案
始终指定 cmake
cmake_minimum_required(VERSION 3.9)
您应声明一个项目。 cmake
说这是强制性的,它将定义方便的变量 PROJECT_NAME
, PROJECT_VERSION
和 PROJECT_DESCRIPTION
(后一个变量需要cmake 3.9):
You should declare a project. cmake
says it is mandatory and it will define convenient variables PROJECT_NAME
, PROJECT_VERSION
and PROJECT_DESCRIPTION
(this latter variable necessitate cmake 3.9):
project(mylib VERSION 1.0.1 DESCRIPTION "mylib description")
声明一个新的库目标。请避免使用 file(GLOB ...)
。此功能不提供对编译过程的熟练掌握。如果您很懒,请复制粘贴输出 ls -1 sources / *。cpp
:
Declare a new library target. Please avoid the use of file(GLOB ...)
. This feature does not provide attended mastery of the compilation process. If you are lazy, copy-paste output of ls -1 sources/*.cpp
:
add_library(mylib SHARED
sources/animation.cpp
sources/buffers.cpp
[...]
)
设置 VERSION
属性(可选,但这是一个好习惯):
Set VERSION
property (optional but it is a good practice):
set_target_properties(mylib PROPERTIES VERSION ${PROJECT_VERSION})
您还可以将 SOVERSION
设置为主要的 VERSION
。因此, libmylib.so.1
将是 libmylib.so.1.0.0
的符号链接。
You can also set SOVERSION
to a major number of VERSION
. So libmylib.so.1
will be a symlink to libmylib.so.1.0.0
.
set_target_properties(mylib PROPERTIES SOVERSION 1)
声明您的库的公共API。将为第三方应用程序安装此API。将其隔离在项目树中是一个好习惯(例如将其放置在 include /
目录中)。请注意,不应安装私有头,我强烈建议将它们与源文件放置在一起。
Declare public API of your library. This API will be installed for the third-party application. It is a good practice to isolate it in your project tree (like placing it include/
directory). Notice that, private headers should not be installed and I strongly suggest to place them with the source files.
set_target_properties(mylib PROPERTIES PUBLIC_HEADER include/mylib.h)
如果使用子目录,则包括相对路径不是很方便例如 ../ include / mylib.h
。因此,在包含的目录中传递顶级目录:
If you work with subdirectories, it is not very convenient to include relative paths like "../include/mylib.h"
. So, pass a top directory in included directories:
target_include_directories(mylib PRIVATE .)
或
target_include_directories(mylib PRIVATE include)
target_include_directories(mylib PRIVATE src)
为库创建安装规则。我建议使用在 GNUInstallDirs
中定义的变量 CMAKE_INSTALL_ * DIR
:
Create an install rule for your library. I suggest to use variables CMAKE_INSTALL_*DIR
defined in GNUInstallDirs
:
include(GNUInstallDirs)
并声明要安装的文件:
install(TARGETS mylib
LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
PUBLIC_HEADER DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
您也可以导出 pkg-config
文件。此文件允许第三方应用程序轻松导入您的库:
You may also export a pkg-config
file. This file allows a third-party application to easily import your library:
- 带有Makefile,请参见
pkg-config
- Autotools,请参见
PKG_CHECK_MODULES
- 带有cmake,请参见
pkg_check_modules
- with Makefile, see
pkg-config
- with Autotools, see
PKG_CHECK_MODULES
- with cmake, see
pkg_check_modules
创建名为 mylib.pc的模板文件.in
(请参见 pc(5 )联机帮助页以获取更多信息):
Create a template file named mylib.pc.in
(see pc(5) manpage for more information):
prefix=@CMAKE_INSTALL_PREFIX@
exec_prefix=@CMAKE_INSTALL_PREFIX@
libdir=${exec_prefix}/@CMAKE_INSTALL_LIBDIR@
includedir=${prefix}/@CMAKE_INSTALL_INCLUDEDIR@
Name: @PROJECT_NAME@
Description: @PROJECT_DESCRIPTION@
Version: @PROJECT_VERSION@
Requires:
Libs: -L${libdir} -lmylib
Cflags: -I${includedir}
在您的 CMakeLists.txt
中,添加一个扩展规则 @
宏( @ONLY
要求cmake不扩展 $ {VAR形式的变量}
):
In your CMakeLists.txt
, add a rule to expand @
macros (@ONLY
ask to cmake to not expand variables of the form ${VAR}
):
configure_file(mylib.pc.in mylib.pc @ONLY)
最后,安装生成的文件:
And finally, install generated file:
install(FILES ${CMAKE_BINARY_DIR}/mylib.pc DESTINATION ${CMAKE_INSTALL_DATAROOTDIR}/pkgconfig)
您还可以使用 cmake 导出
功能。但是,此功能仅与 cmake
兼容,我觉得很难使用。
You may also use cmake EXPORT
feature. However, this feature is only compatible with cmake
and I find it difficult to use.
最后整个 CMakeLists.txt
应该看起来像:
Finally the entire CMakeLists.txt
should looks like:
cmake_minimum_required(VERSION 3.9)
project(mylib VERSION 1.0.1 DESCRIPTION "mylib description")
include(GNUInstallDirs)
add_library(mylib SHARED src/mylib.c)
set_target_properties(mylib PROPERTIES
VERSION ${PROJECT_VERSION}
SOVERSION 1
PUBLIC_HEADER api/mylib.h)
configure_file(mylib.pc.in mylib.pc @ONLY)
target_include_directories(mylib PRIVATE .)
install(TARGETS mylib
LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
PUBLIC_HEADER DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
install(FILES ${CMAKE_BINARY_DIR}/mylib.pc
DESTINATION ${CMAKE_INSTALL_DATAROOTDIR}/pkgconfig)
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