Erlang hooks application. It allows adding tasks dynamically to predefined hooks.
In your rebar.config file, add the dependency:
{deps, [
{nhooks, {git, "[email protected]:nomasystems/nhooks.git", {branch, "main"}}}
]}.Assuming there is a module named test_app that has one hook named init and another named terminate:
-module(test_app).
%%% EXTERNAL EXPORTS
-export([init/1, terminate/1]).
%%% NHOOKS EXPORTS
-export([hooks/0]).
%%%-----------------------------------------------------------------------------
%%% EXTERNAL EXPORTS
%%%-----------------------------------------------------------------------------
init(Term) ->
nhooks:do(?MODULE, init, [Term]).
terminate(Term) ->
nhooks:do(?MODULE, terminate, [Term]).
hooks() ->
[
init,
terminate
].
You can register tasks to the defined hooks:
%%% Registering tasks in both hooks
ok = nhooks:register_task(test_app, init, fun(Term) ->
do_something(Term)
end).
ok = nhooks:register_task(test_app, terminate, fun(Term) ->
do_something_else(Term)
end).
From now on when test_app executes the init and terminate hooks the registered tasks will be executed.
You can also register multiple tasks to any defined hook:
%%% Registering multiple tasks to same hook
ok = nhooks:register_task(test_app, init, fun(Term) ->
do_something(Term)
end).
ok = nhooks:register_task(test_app, init, fun(Term) ->
do_something_else(Term)
end).
And all will be executed when test_app executes the init hook.
If you want to stop the subsequent tasks from executing, you can return stop or {stop, Data} from any task. For example:
%%% Stopping subsequent tasks in the same hook
ok = nhooks:register_task(test_app, init, fun(Term) ->
do_something(Term),
{stop, {some, data}}
end).
ok = nhooks:register_task(test_app, init, fun(Term) ->
do_something_else(Term)
end).
In this case, the second task won't be executed and the call to nhooks:do/3 will return {stopped, {some, data}}.
All tasks are registered with a default priority of 0 and then executed from lowest to highest priority. That priority can be passed as the last argument of nhooks:register_task/4:
ok = nhooks:register_task(test_app, init, fun(_Term) -> first end, -1).
ok = nhooks:register_task(test_app, init, fun(_Term) -> second end).
ok = nhooks:register_task(test_app, init, fun(_Term) -> third end, 5).
Any doubt or suggestion? Please check out our issue tracker.