beh.ex

defmodule Behaviours.Telegram do
  @moduledoc false
  @callback sendInfo(accountId :: term, info :: term) :: {:ok}
end

macro.ex

defmodule TelegramModule do
  @moduledoc false

  defmacro __using__(opts) do
    reg = Keyword.get(opts, :reg)
    quote do
      @behaviour Behaviours.Telegram
      def start_link(accountId) do
        name = via_tuple(accountId)
        GenServer.start_link(__MODULE__, [accountId], name: name)
      end

      defp via_tuple(accountId) do
        {:via, Registry, {unquote(reg), accountId}}
      end

      def sendInfo(accountId, info) do
        GenServer.cast(via_tuple(accountId), info)
      end
    end
  end
end

module.ex

defmodule Start do
  @moduledoc false
  use TelegramModule, reg: :process_registry
  use GenServer

  def init(_opts) do
    {:ok, %{}}
  end

  def handle_cast(_msg, state) do
    {:noreply, state}
  end
end