Code Dependencies

The Mix tool is smart when it compiles a project. It analyzes the dependencies between our source files and only recompiles a file when it has changed or a file it depends on has changed. As developers, we can also access this dependency information, gaining valuable insights into our code. We do this with the mix xref commands:

• The mix xref unreachable command lists functions that are unknown at the time they are called.

• The mix xref warnings command lists warnings associated with dependencies (for example, calls to unknown functions).

• The mix xref callers Mod | Mod.func | Mod.func/arity command lists the callers to a module or function:

$ mix xref callers Logger
mix xref callers Logger
web/controllers/page_controller.ex:1: Logger.bare_log/3
web/controllers/page_controller.ex:1: Logger.debug/1
lib/webapp/endpoint.ex:1: Logger.bare_log/3
lib/webapp/endpoint.ex:1: Logger.error/1

• The mix xref graph command shows the dependency tree for the application: