CODEWITHSUNDEEP
c++cmakeinclude-path
Paul D.
Paul D.

Reputation: 1845

How to easily include headers from library dependency in cmake circa v2.8.8

I'm experimenting with CMake a bit for a C++ repository, but I'm running into some trouble trying to make it easy to build applications against libraries in the same source tree without a lot of extra CMake code.

The layout of the source tree is basically the following:

ROOT
    libs/
         lib1/
         lib2/
         lib3/
    apps/
         app1/
         app2/
         app3/

The libraries are independent of one another, and the applications may link against one or more of the libraries.

Currently I have a root CMakeLists.txt that lists out each application and library as a subdirectory so that if the library is changed and the application is rebuilt, so is the library. This works fine and CMake links it in without me having to specify where the library lives, but I don't see a way to do something similar for include directories.

Is there a common way to handle this? I'd prefer not to have each application's CMakeLists.txt have to manually list out the path to the libraries it needs.

Upvotes: 5

Views: 668

Answers (2)

starball
starball

Reputation: 50269

This question is pretty old. It was asked on 2012-07-18. I'm adding an answer here to attempt to explain some history. Warning: I may have gotten it wrong or misunderstood the history.

At that time, the latest non-release-candidate relase was CMake v2.8.8 (released on 2012-04-18). The INCLUDE_DIRECTORIES target property already existed in v2.8.8, but there was no corresponding INTERFACE_INCLUDE_DIRECTORIES target property yet. Its target_link_libraries documentation didn't say anything about a target automatically adding the include directories of the targets it depended upon.

About ten months after this question was asked (2012-07-18), CMake v.2.8.11 was released. It added the target_include_directories command signature with the INTERFACE|PUBLIC|PRIVATE argument, and added the INTERFACE_INCLUDE_DIRECTORIES target property.

So you can create a target B, specify public/interface include directories for it, and then make a target A depend on it via target_linK_libraries, and then A will automatically add/use the include directories of B. That can be made transitive by making the link public/interface, or non-transitive by making the link private.

You can find Kitware's list of software releases here, and a list of the documentation revisions here.

Upvotes: 0

languitar
languitar

Reputation: 6784

If you are not afraid of making more headers available than you actually need for each application, you could list all lib directories in an INCLUDE_DIRECTORIES statement e.g. in the CMakeListst.txt adding all application sublists. But there is no such concept of managing "belonging" include folders per target built-in.

Upvotes: 1

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