详细解释：参考文档http://erlangdisplay.iteye.com/blog/315391 上面代码好多错误
-module(recent_logger).
-behaviour(gen_event).
-export([start/0, stop/0, log/1, report/0, release/0]).
%% gen_event callbacks
-export([init/1, handle_event/2, handle_call/2, terminate/2,add_handler/0]).
-define(NAME, logger_manager).
add_handler()->
gen_event:add_handler(?NAME, ?MODULE, [testinit]).
%% start behaviour
start() ->
case gen_event:start_link({local, ?NAME}) of
Ret = {ok, _Pid} ->
% gen_event:add_handler(?NAME, ?MODULE, [testinit]),
Ret;
Other ->
Other
end.
%% stop
stop() ->
gen_envent:stop(?NAME).
%% notify an envent about log
log(E) ->
gen_event:notify(?NAME, {log, E}).
%% report the all log
report() ->
gen_event:call(?NAME, ?MODULE, report).
%% release this handler
release() ->
gen_event:delete_handler(?NAME, ?MODULE, release).
init(_Arg) ->
io:format("start recent log handler Arg=~p~n",[_Arg]),
{ok, []}.
handle_event({log, E}, List) ->
io:format("long E=~p, List=~p~n",[E,List]),
{ok, trim([E | List])}.
handle_call(report, List) ->
{ok,List,List} .
terminate(stop, _List) ->
io:format("recent log handler stop~n"),
ok;
terminate(release, _List) ->
io:format("recent log handler release~n"),
ok.
%% save the recent five log
trim([E1, E2, E3, E4, E5 | []]) ->
[E1, E2, E3, E4, E5];
trim(List) ->
List.
