Can we import types and guards from another module?

Questions / Help
,
1

Given this module:

defmodule A do
  @type size :: pos_integer()
  defguard is_size(x) when is_integer(x) and x > 0
  def default_size(), do: 1
end

…how do we make the below work without prefixes?

defmodule B do
  @type t :: %__MODULE__{size: size()}
  defstruct [size: default_size()]
  def put_size(opts, size) when is_list(opts) and is_size(size), do: Keyword.put(opts, :size, size)
end

Tried import A and require A, both don’t get the job done.

What elementary Elixir lesson I managed to forget?

4 Likes
2

You should be able to import is_size/1 just by doing import A(, only: [is_size: 1]).

You can not import types though. The easiest way is to just alias them.

@type foo :: Foo.foo
15 Likes
3

Yeah. I just import the guards and prefix the types. Seems there’s no actual seamless way to import everything in one go without any prefixes. Thank you.

4

You might also group your types into a module like so


defmodule MyApp.Types do

    defmacro __using__(_opts) do 
          quote do
             @type greek_t :: :alpha | :beta
             @type mystruct_t :: MyApp.MyStruct.t # Beware of circulars here!!
          end
    end
...
9 Likes