I like Erlang and I like gen_servers, I end up coding a lot of stuff as gen_servers and I like behaviors in generally. I even wrote some myself. I haven’t used Erlang for a while. I’ve been playing with it in the last couple of days, hopefully I’ll announce something soon.
I ended up creating my own gen_servers template to get started. It’s a very verbose one and I’m putting it here more for me to know where it is that anything else; but, maybe it’s of use for someone else:
-module(module).
-compile(export_all).
-behaviour(gen_server).
-export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2, code_change/3]).
%% Public API
start() ->
gen_server:start({local, ?MODULE}, ?MODULE, [], []).
stop(Module) ->
gen_server:call(Module, stop).
stop() ->
stop(?MODULE).
state(Module) ->
gen_server:call(Module, state).
state() ->
state(?MODULE).
%% Server implementation, a.k.a.: callbacks
init([]) ->
say("init", []),
{ok, []}.
handle_call(stop, _From, State) ->
say("stopping by ~p, state was ~p.", [_From, State]),
{stop, normal, stopped, State};
handle_call(state, _From, State) ->
say("~p is asking for the state.", [_From]),
{reply, State, State};
handle_call(_Request, _From, State) ->
say("call ~p, ~p, ~p.", [_Request, _From, State]),
{reply, ok, State}.
handle_cast(_Msg, State) ->
say("cast ~p, ~p.", [_Msg, State]),
{noreply, State}.
handle_info(_Info, State) ->
say("info ~p, ~p.", [_Info, State]),
{noreply, State}.
terminate(_Reason, _State) ->
say("terminate ~p, ~p", [_Reason, _State]),
ok.
code_change(_OldVsn, State, _Extra) ->
say("code_change ~p, ~p, ~p", [_OldVsn, State, _Extra]),
{ok, State}.
%% Some helper methods.
say(Format) ->
say(Format, []).
say(Format, Data) ->
io:format("~p:~p: ~s~n", [?MODULE, self(), io_lib:format(Format, Data)]).
Update 2010-01-04: I keep changing the actual contents of the template as I’m coding a little Erlang app. I’ve recently added, among other things, a call to get the state of the process, useful for debugging.
