How to run custom code at bot startup?

[aus70]

I'd like to run set_my_command, set_my_description, set_my_name and some other initialization code at bot startup. What's the best way to do it?
Thanks!

[rockneurotiko]

Currently there are not an easy way of dealing with this, but I'll add an optional init/1 callback on the bot so this inital setup is easy

[aus70]

that'd be great, thanks!

[manuel-rubio]

The problem I found with init/1 is that it's running from the Supervisor init, and that means the Dispatcher is still not running. Even more, it's a mess if we want to use Phoenix.PubSub for receiving information inside of the Dispatcher because it only could be done by performing a request to the Dispatcher, not when the dispatcher is up and running.

I suggest init/1 callback for Bot be moved to Dispatcher when the connection is up and working, or that we could define any hooks/triggers/callbacks for when the connection is up and running (handle_up/1) and previously to that (init/1 but inside of the Dispatcher).

[rockneurotiko]

@manuel-rubio What's the use case for needing the Dispatcher started in the init/1 callback?

If you are trying to link a bot with Phoenix.PubSub in order to receive broadcast messages, I don't think subscribing from the dispatcher is a good thing. I would definitely go with my own Supervisor, with the Bot and a GenServer to handle the subscription, then the GenServer can send messages to the bot manually (Either with BotModule.message(<origin>, <message>) or with GenServer.call(<:bot_name>, <message>)

[manuel-rubio]

I did it in that way, but it's weird to have a GenServer only for sending messages to another process.

defmodule MyProject.Bot.Proxy do
  use GenServer

  def init([]) do
    Phoenix.PubSub.subscribe(MyProject.PubSub, "topic1")
    {:ok, nil}
  end

  def handle_info(info, nil) do
    send(MyProject.Bot.name(), info)
    {:ok, nil}
  end
end

It's not providing value at all and it's needed only because I cannot run startup code inside of the Dispatcher process.

My problem with that is I put in the init/1 the PubSub subscriptions and suddenly we have messages from the supervisor saying it receives an unexpected message, it sounded not very intuitive for me that init/1 was running in the supervisor process and handle/2 is running in the Dispatcher process, based on GenServer I was expecting both running on the same process.