snippet.ex

defmodule MyApp.Snippet do
  defmacro defsnippet(name, do: snippet) do
    quote do
      snippets = Module.get_attribute(__MODULE__, :snippets) || []
      snippets = [{unquote(name), unquote(snippet)} | snippets]

      Module.put_attribute(__MODULE__, :snippets, snippets)
    end
  end

  defmacro snippet(name) do
    quote do
      case Enum.find(@snippets, fn {k, _v} -> k == unquote(name) end) do
        {_name, snippet} -> snippet
        nil -> raise "Snippet #{unquote(name)} not found"
      end
    end
  end
end