Extract gettext translations inside macro

I’d love if Gettext.Extractor could become public api. I had asked for that a few months back on a more esoteric usecase and given the usecase the response was negative. This sounds more in line with the libraries goals. But I wonder why you cannot provide binary literals if you’re in a macro context.

Glad to hear that not only me is looking for this.

This is about said data argument in some_dsl macro, see:

Ah, yeah. You’d cannot work with variables, you need to know the actual strings in your macro.

I believe you should be able to use the exposed public APIs in Macros since you can just unquote the variable containing the string.

require Gettext.Macros

for message <- ["message 1", "message 2"] do
  def translate(unquote(message)) do
    Gettext.Macros.dgettext_with_backend(
      Acme.Gettext,
      "default",
      unquote(message)
    )
  end
end

See Gettext.Macros — gettext v1.0.2

I have mentioned it as alternative way in 2nd point and why it’s not an option for me. For now I’m investigating expo as generating pot file sounds like an interesting alternative to current solutions.

Generally when using macros, you should have access to the literal and not just the variable. Can you share a simplified version of your DSL that shows the issue?

It’s the intention of gettext that this works. If it does not, we’ll need to have a closer look.

I’m not sure I fully understand your use case but in a project I work on we extract translations from the .POT file. Seems to work fine, we hand rolled a parser of those files but I think Expo.PO.parse_file!("priv/gettext/default.pot") probably works fine

Here you go:

defmodule DummyGettext do
  defmacro dummy_macro(input, _lang \\ "en") do
    # gettext macros require literals at this point (not within quote do … end block)
    IO.inspect(input)
    is_binary(input) == false && raise "gettext fail here"
  end

  def get_locales, do: ["en"]
end

defmodule MyLib.DSL do
  defmacro __using__(_opts \\ []) do
    quote do
      import MyLib.DSL

      require DummyGettext

      def translated_input(input, locale \\ "en")
    end
  end

  defmacro some_dsl(input) do
    for locale <- DummyGettext.get_locales() do
      translated_input = quote do: DummyGettext.dummy_macro(unquote(input))

      quote bind_quoted: [input: input, locale: locale, translated_input: translated_input] do
        def translated_input(unquote(input), unquote(locale)), do: unquote(translated_input)
      end
    end
  end
end

defmodule MyApp.Example do
  use MyLib.DSL

  # this one obviously works
  some_dsl("text to translate")

  # my macros are fine with that, but gettext requires literal at compile time
  # so below code fails
  for data <- ~w[first second third] do
    some_dsl(data)
  end
end

Wrong way. I think now about generating .pot file at compile time and then call mix gettext.merge priv/gettext --locale locale. It’s nothing related to parsing .pot file. Sorry if my post was not clear enough.

Generating a .pot file using expo is definitely the best solution. I have a full control over code, I don’t need to worry about private APIs and it’s also a very simple thing to do.