Feature request: Allow getting partials from other sources

[aptinio]

In our Elixir project, we couldn't save partials in the filesystem. To work around this, we wrapped bbmustache like so:

defmodule OurApp.Mustache do
  @partial_templates %{
    foo: "Foo",
    bar: "Bar"
  }

  def render(bin, data) do
    {:bbmustache, tags, partial_keys, options, indents, context_stack} =
      :bbmustache.parse_binary(bin)

    :bbmustache.compile(
      {
        :bbmustache,
        tags,
        parse_remaining_partials(partial_keys, [], []),
        options,
        indents,
        context_stack
      },
      data,
      key_type: :atom,
      raise_on_context_miss: true
    )
  end

  defp parse_remaining_partials([] = _keys, partials, _parsed_keys), do: partials

  defp parse_remaining_partials([key | rest_of_keys], partials, parsed_keys) do
    if key in parsed_keys do
      parse_remaining_partials(rest_of_keys, partials, parsed_keys)
    else
      bin = Map.fetch!(@partial_templates, String.to_existing_atom(key))

      {:bbmustache, tags, nested_keys, _options, _indents, _context_stack} =
        :bbmustache.parse_binary(bin)

      parse_remaining_partials(rest_of_keys ++ nested_keys, [{key, tags} | partials], [
        key | parsed_keys
      ])
    end
  end
end

However, dialyzer is complaining about the opacity of :bbmustache.template() being broken because it is matched against a pattern.

It would be nice if :bbmustache.template() weren't opaque. Better yet, it would be nice if :bbmustache.parse_option() allows get_partial_fun which defaults to the current implementation of reading the partial from a file.

I'd love to submit a PR but my Erlang skills are severely lacking.

[soranoba]

I understand your motivation and difficult to use local file I/O on many systems.

I think that it should keep bbmustache::template() is opaque, because bbmustache does not want to make any changes to the data structure externally.
If it changes, backward compatibility will be difficult.

It is a good policy to add an option to parse_option.

[soranoba]

https://github.com/soranoba/bbmustache/tree/v1.9.0
released.

[aptinio]

Thank you so much!