Gettext domains with code generation

Questions / Help
,
1

I’m trying to create some translations for my CMS resources, and I’m trying to automatically create Gettext domains for each resource.

defmodule MyApp.Projects.Project do
  use B.Blueprint
  import MyApp.Gettext

  @singular "project"
  @plural "projects"

  # these macros basically build a map of translations
  translations do
    context :fields do
      translate :title do
        label t("Some label text")
        placeholder t("Some placeholder")
      end
    end
  end
end

The t macro lives in the used B.Blueprint and looks like this:

 # ...
  # 
  defmacro t(msgid) do
    quote do
      dgettext(@plural, msgid)
    end
  end

This doesn’t work of course:

** (ArgumentError) Gettext macros expect translation keys (msgid and msgid_plural),
domains, and comments to expand to strings at compile-time, but the given domain
doesn't. This is what the macro received:

{{:., [], [{:__aliases__, [counter: {MyApp.Projects.Project, 58}, alias: false], [:Module]}, :__get_attribute__]}, [], [{:__MODULE__, [counter: {MyApp.Projects.Project, 58}], Kernel}, :plural, 83]}

Is this doable in any way? I was hoping to not having to put all my translations in the “default.pot” file, and also not having to do t("projects", "msg here") :slight_smile:

2

Something like this should do the trick however for some reason Module.get_attribute/2 is returning nil which I did not expect. My early morning brain isn’t resolving why so putting here so smarter brains can clarify.

defmodule B.Blueprint do
  defmacro t(msgid) do
    caller = __CALLER__.module

    # On my quick test this is returning `nil` which surprised me
    domain = Module.get_attribute(caller, :plural)

    # Testing this way works
    domain = "plural"

    quote do
      dgettext(unquote(domain), unquote(msgid))
    end
  end

end

defmodule MyApp.Projects.Project do
  import MyApp.Gettext
  import B.Blueprint

  @plural "projects"

  t("some message")
end
1 Like
3

Thanks for the __CALLER__.module hint!

I did some logging and it seems that the t macro is run before the module attribute is set, so I had to do a slight API adjustment:

defmodule MyApp.Projects.Project do
  use B.Blueprint, 
    singular: "Project",
    plural: "Projects"

  import MyApp.Gettext

  # these macros basically build a map of translations
  translations do
    context :fields do
      translate :title do
        label t("Some label text")
        placeholder t("Some placeholder")
      end
    end
  end
end

then in B.Blueprint

  defmacro __using__(opts) do
    Module.register_attribute(__CALLER__.module, :singular, accumulate: false)
    Module.put_attribute(__CALLER__.module, :singular, Keyword.fetch!(opts, :singular))

    Module.register_attribute(__CALLER__.module, :plural, accumulate: false)
    Module.put_attribute(__CALLER__.module, :plural, Keyword.fetch!(opts, :plural))
    # ...

Now the module attribute is available in my t macro! :tada:

4

Cool, I think thats a better and more obvious API too. Glad its up and running for you!

1 Like
5

I’m having the same wish you do. But I’m failing to get this to work.

What is this B.Blueprint? And where does that code live?

I’ve tried to make a translations.ex (in the same location as utils.ex)

defmodule Translations do
  defmacro tr(msgid) do
    domain = "plural"

    quote do
      dgettext(unquote(domain), unquote(msgid))
    end
  end

  defmacro __using__(opts) do
    Module.register_attribute(__CALLER__.module, :singular, accumulate: false)
    Module.put_attribute(__CALLER__.module, :singular, Keyword.fetch!(opts, :singular))

    Module.register_attribute(__CALLER__.module, :plural, accumulate: false)
    Module.put_attribute(__CALLER__.module, :plural, Keyword.fetch!(opts, :plural))
  end

end

But using it proves difficult :frowning:

use Translations, plural: "menus", singular: "menu"

def public_menu_items(_user \\ nil),
    do: [
      %{label: tr("Features"), path: "/#features"},
    ]
end


== Compilation error in file lib/cavalato_web/menus.ex ==
** (CompileError) lib/cavalato_web/menus.ex:13: undefined function tr/1 (expected CavalatoWeb.Menus to define such a function or for it to be imported, but none are available)

Obviously, when doing this it doesn’t crash, but it also doesn’t do the translating :thinking:

use Translations, plural: "menus", singular: "menu"

def public_menu_items(_user \\ nil),
    do: [
      %{label: Translations.tr("Features"), path: "/#features"},
    ]
end