导入目标库和接口库之间有什么区别？ [英] What are the differences between IMPORTED target and INTERFACE libraries?

问题描述

据我了解，接口库就像 Visual Studio属性表一样，非常有用。我们可以使用它来链接静态库并传播属性。

As I understand it INTERFACE libraries are like Visual Studio property sheets, so very useful. We can use it to link with static libs and propagate properties.

但是导入目标困扰着我：我看不到只能使用导入目标才能解决的问题。

But IMPORTED targets bother me : I can't see a problem which can be solved with IMPORTED target only.

推荐答案

创建导入的目标时，您在告诉CMake：我有这个{静态库|共享库|模块库|可执行文件}已在磁盘上的此位置构建。我希望能够像对待由自己的构建系统构建的目标一样对待它，因此请注意，当我说 ImportedTargetName 时，它应该引用磁盘上的该二进制文件（带有

When you create an imported target, you're telling CMake: I have this { static library | shared library | module library | executable } already built in this location on disk. I want to be able to treat it just like a target built by my own buildsystem, so take note that when I say ImportedTargetName, it should refer to that binary on disk (with the associated import lib if applicable, and so on).

创建接口库时，您在告诉CMake：我有这组属性（包括目录等）。 。）客户端可以使用的客户端，因此，如果它们链接到我的接口库，请将这些属性传播给他们。

When you create an interface library, you're telling CMake: I have this set of properties (include directories etc.) which clients can use, so if they "link" to my interface library, please propagate these properties to them.

根本的区别是不支持接口库根据磁盘上的任何内容，它们只是一组需求/属性。您可以可以根据需要在接口库上设置 INTERFACE_LINK_LIBRARIES 属性，但这并不是它们的初衷。它们将封装客户端消耗的属性，并且主要对诸如C ++中的仅标头库之类的东西有意义。

The fundamental difference is that interface libraries are not backed by anything on disk, they're just a set of requirements/properties. You can set the INTERFACE_LINK_LIBRARIES property on an interface library if you really want to, but that's not really what they were designed for. They're to encapsulate client-consumable properties, and make sense primarily for things like header-only libraries in C++.

还要注意，接口库是库-没有接口可执行文件，但是您确实可以导入可执行文件。例如。 Bison的程序包配置文件可以为Bison可执行文件定义导入的目标，然后您的项目可以将其用于自定义命令：

Also notice that an interface library is a library—there's no such thing as an interface executable, but you can indeed have imported executables. E.g. a package config file for Bison could define an imported target for the Bison executable, and your project could then use it for custom commands:

# In Bison package config file:
add_executable(Bison IMPORTED)
set_property(TARGET Bison PROPERTY IMPORTED_LOCATION ...)

# In your project:
find_package(Bison)
add_custom_command(
  OUTPUT parser.c
  COMMAND Bison tab.y -o parser.c
  DEPENDS tab.y
  ...
)

（野牛只是作为您可能要在自定义命令中使用的示例，命令行可能不合适）。

(Bison is used just as an example of something you might want to use in custom commands, and the command line is probably not right for it).

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