Can I share sections of mix.exs files between umbrella child apps?

Questions / Help
,
1

I have a lot of duplication between the mix.exs files in my umbrella child apps.

defmodule Foo.Mixfile do
  use Mix.Project

  def project do
    [
      some_key: %{
        some_big_data_structure: {
          ...
        }
    ]
  end
end

I have tried to import the shared code into them from a module:

defmodule Foo.Mixfile do
  use Mix.Project
  import SharedStuffModule
...

But I get:

module SharedStuffModule is not loaded and could not be found

I suppose the config must get read before loading other modules or similar…

Is there any way around this in Elixir? I’d very much like to DRY a few bigs of very long duplication between mix.exs files.

Thanks!

2

Probably not what you are looking for, but you can create yet another app which would export the shared data as a function?

# in the new `_shared` app
defmodule _Shared do
  def common_project(some, variables) do
    # ...
  end
end

Or maybe you can read the shared configs from the filesystem in some way?

3

Because it is a script file (.exs), any dependency needs to be explicitly required/loaded.

So you can put the SharedStuffModule in the umbrella root in a file named “shared_stuff.exs” and then on each umbrella child you can add at the top:

Code.require_file "../../shared_stuff.exs", __DIR__

Note though that the umbrella children were designed so they don’t depend on the parent, so this will slightly break this assumption.

3 Likes
4

Thanks very much @josevalim! That worked perfectly.