What OTP behaviors should I use for such module?

Question

I have simple erlang module and I want to rewrite it based on OTP principles. But I can not determine what opt template I should use.

Module's code:

-module(main).

-export([start/0, loop/0]).

start() -> 
    Mypid = spawn(main, loop, []),
    register( main, Mypid).

loop() ->
    receive
        [Pid, getinfo] -> Pid! [self(), welcome],
            io:fwrite( "Got ~p.~n", [Pid] ),
            // spawn new process here
            loop();
        quit -> ok;
        X ->
            io:fwrite( "Got ~p.~n", [ X ] ),
            // spawn new process here
            loop()
    end.

user425720 user425720 · Accepted Answer · 2012-06-05T05:01:10

gen_server would be fine.

Couple things:

it is a bad practice to send message to yourself
messages are usually tuples not lists because they are not dynamic
despite your comment, you do not spawn the new process. Call to loop/0 enters the same loop.

Gen_server init would hold your start/0 body. API calls sequence and proxy your calls via gen_server to handle_calls. To spawn new process on function call, add spawn function to the body of desired handle_call. Do not use handle_info to handle incoming messages -- instead of sending them call the gen_server API and 'translate' your call into gen_server:call or cast. e.g.

start_link() ->
    gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).

init(_) ->
    {ok, #state{}}

welcome(Arg) ->
   gen_server:cast(?MODULE, {welcome, Arg}).

handle_cast({welcome, Arg},_,State) ->
  io:format("gen_server PID: ~p~n", [self()]),
  spawn(?MODULE, some_fun, [Arg]),
  {noreply, State}

some_fun(Arg) ->
  io:format("Incoming arguments ~p to me: ~p~n",[Arg, self()]).

I have never compiled above, but it should give you the idea.

What OTP behaviors should I use for such module?

1 Answers