Introduction to cmake

Flux Capacitor Library

Command target_link_libraries is used to specify dependencies. Requirements for include directories are defined with command target_include_directories as seen before.

Both commands support the keywords PRIVATE, PUBLIC and INTERFACE to specify the usage requirements:

• PRIVATE Needed by me, but not my dependants.
• PUBLIC Needed by me and my dependants.
• INTERFACE Not needed by me, but by my dependants only.

Attention: Build targets that have source files should always list the files explicitly. Using a mechanism like file globing hides dependencies and prevents the build tools from correctly resolve build dependencies.

Example:

add_library(apple
  src/apple.cc
  src/peel.cc
)
add_library(fruit::apple ALIAS apple)

target_include_directories(apple
  PUBLIC include
)

target_link_libraries(apple
  PRIVATE fruit::seeds
  PUBLIC fruit::edible
)

Exercise 3

Add library flux_capacitor to the project. As usual also add an alias target named time_machine::flux_capacitor.

[project]/
+--- CMakeLists.txt
+--- flux_capacitor/
|    +--- CMakeLists.txt
|    +--- include/
|    |    +--- flux_capacitor/
|    |         +--- flux_capacitor.h
|    +--- src/
|         +--- capacitor.cc
|         +--- capacitor.h
|         +--- flux_capacitor.cc
|         +--- flux.cc
|         +--- flux.h
|
+--- ...

The library has three source files: src/capacitor.cc, src/flux.cc and src/flux_capacitor.cc.

The library is implementing the time_travel interface. It is used by the library and also part of its own public interface. So the time_machine::time_travel interface is a public dependency.

Also, don't forget to add the project::settings as a private dependency.

The include folder is a public include directory.