My custom OTP behaviour for event management

README

Do you want to try it?

---

1st. Compile

    $ erlc gen_event_manager.erl my_event_manager.erl my_event.erl

2nd. Test

    $ erl
    Erlang R14A (erts-5.8) [source] [64-bit] [smp:2:2] [rq:2] [async-threads:0] [hipe] [kernel-poll:false]

    Eshell V5.8  (abort with ^G)
    1> my_event_manager:start_link().
    {ok,[]}
    2> my_event_manager:add_handler(my_event, []).
    ok
    3> my_event_manager:which_handlers().
    [my_event]
    4> my_event_manager:notify_event("java").     
    --> event: [106,97,118,97]
    ok

gen_event_manager.erl

-module(gen_event_manager).

-export([start_link/3]).
-export([behaviour_info/1]).

start_link(ServerName, CallbackModule, Args) ->
  gen_event:start_link(ServerName),
  CallbackModule:init(Args).
  
behaviour_info(callbacks) ->
  [{init, 1},
   {add_handler, 2},
   {delete_handler, 2},
   {swap_handler, 2},
   {which_handlers, 0},
   {notify_event, 1}].

my_event.erl

-module(my_event).
-behaviour(gen_event).

-export([init/1, handle_event/2, terminate/2, handle_call/2, handle_info/2, code_change/3]).

init(_Args) ->
  {ok, []}.
  
handle_event(Event, State) ->
  io:format("--> event: ~w~n", [Event]),
  {ok, State}.
  
terminate(_Args, _State) ->
  ok.

handle_call(_Request, _State) -> ok.

handle_info(_Info, _State) -> ok.

code_change(_OldVsn, State, _Extra) -> {ok, State}.

my_event_manager.erl

-module(my_event_manager).
-behaviour(gen_event_manager).

-export([start_link/0]).
-export([init/1, add_handler/2, delete_handler/2, swap_handler/2, which_handlers/0, notify_event/1]).

%% api

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

%% callbacks

init(_Args) ->
  {ok, []}.

add_handler(HandlerModule, InitArgs) ->
  gen_event:add_handler(?MODULE, HandlerModule, InitArgs).
  
delete_handler(HandlerModule, State) ->
  gen_event:delete_handler(?MODULE, HandlerModule, State).

swap_handler({_OldHandlerModule, _TerminateArgs} = Old, {_NewHandleModule, _InitHandler} = New) ->
  gen_event:swap_handler(?MODULE, Old, New).
  
which_handlers() ->
  gen_event:which_handlers(?MODULE).
  
notify_event(Event) ->
  gen_event:notify(?MODULE, Event).