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Make the code more DRY and more flexible using EventEmitter2.
Add also a way to output a log of the `.trigger` actions The code that was doing event management was copy and pasted in 3 places. Plus it has a mechanism that prevent the unprocessed listeners to execute if a listener return false. This mechanisms is error prone since it depends on the order in which the event listeners (.on) are registered. It seemed that the mechanism was not used beside optimization.
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,129 @@ | ||
| /** | ||
| * Implement a pub sub sing the great EventEmitter2. | ||
| * The basic interface is: | ||
| * trigger(event, [param1, param2, ...]) | ||
| * on(events, function(param1, param2, ...){ ... }) | ||
| * It also log events with stack trace, when the DEBUG options are active | ||
| **/ | ||
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| var EventEmitter2 = require('eventemitter2').EventEmitter2; | ||
| var debug = require('debug'); | ||
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| /** | ||
| * Execute each of the listeners that may be listening for the specified event | ||
| * name in order with the list of arguments. | ||
| * @param {string} event - the event name | ||
| * @param {*[]} [data] - an array of data being passed. | ||
| **/ | ||
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| EventEmitter2.prototype.trigger = function(event, data) { | ||
| var args = [event]; | ||
| if (data) for(var i in data){ | ||
| args.push(data[i]); | ||
| } | ||
| EventEmitter2.prototype.emit.apply(this, args); | ||
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| // for chaining | ||
| return this; | ||
| } | ||
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| var oldOn = EventEmitter2.prototype.on; | ||
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| /** | ||
| * Callback of the on function. | ||
| * The event name is avaiable in this.event | ||
| * | ||
| * @callback eventCallback | ||
| * @param {...*} [opt] - List of arguments passed in the trigger function | ||
| */ | ||
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| /** | ||
| * Adds a listener to the end of the listeners array for the specified event. | ||
| * Support: | ||
| * - simple string as one event | ||
| * - a comma separated string to define multiple events | ||
| * - an array of strings to define multiple events | ||
| * | ||
| * @param {string|string[]} event - the event's name or events' names | ||
| * @param {eventCallback} eventFunction - fuction associated to the event(s) | ||
| **/ | ||
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| EventEmitter2.prototype.on = function (event){ | ||
| var events = (typeof(event) == 'string') ? event.split(/\,/g) : event; | ||
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| //For 1 or not an array | ||
| if (!(events.length >= 2)){ | ||
| oldOn.apply(this, arguments); | ||
| // for chaining | ||
| return this; | ||
| } | ||
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| // For 2+ events | ||
| var l = arguments.length; | ||
| var args = new Array(l); | ||
| for (var i = 1; i < l; i++) args[i] = arguments[i]; | ||
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| for (var i in events) { | ||
| args[0] = events[i]; | ||
| oldOn.apply(this, args); | ||
| } | ||
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| // for chaining | ||
| return this; | ||
| } | ||
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| /** | ||
| * Create a EventEmitter2 | ||
| * Attach also a default tracer when an event is triggered. | ||
| * | ||
| * @param {Object} opt - Options for eventEmitter2 constructor (See https://github.com/asyncly/EventEmitter2#differences-non-breaking-compatible-with-existing-eventemitter) | ||
| **/ | ||
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| EventEmitter2.create = function(opt){ | ||
| var ret = new EventEmitter2(opt); | ||
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| var trace = false; | ||
| if (debug.enabled("botkit:events:stackTrace:trigger")){ | ||
| trace = true; | ||
| } | ||
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| ret.onAny(function(event){ | ||
| if (trace) { | ||
| // NOTE: it is NOT an error! Just an effective way to get a trace. | ||
| var here = new Error("The event Trace"); | ||
| debug("botkit:events:trigger:" + this.event)(arguments, here.stack); | ||
| } else { | ||
| debug("botkit:events:trigger:" + this.event)(arguments); | ||
| } | ||
| }); | ||
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| return ret; | ||
| } | ||
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| /** | ||
| * Utility to add alias `functions` of a object ee in a object o | ||
| * and create an alias of ee as o[member] | ||
| * | ||
| * Ex : EventEmitter2.extendObject(this, EventEmitter2.create()); | ||
| * | ||
| * @param {Object} o - the object that receives the alias function | ||
| * @param {Object} ee - the EventEmitter2 object to be associated with o | ||
| * @param {string} [member] - the alias of the EventEmitter2 in o (default _EE) | ||
| * @param {string[]} [functions] - the names of the function to be aliased | ||
| **/ | ||
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| EventEmitter2.extendObject = function(o, ee, member, functions){ | ||
| if(!member) member = '_EE'; | ||
| if(!functions) functions = ['on', 'off', 'trigger', 'many', 'once']; | ||
| o[member] = ee; | ||
| for (var i in functions){ | ||
| var f = functions[i]; | ||
| // create o.on = o._EE.on ... etc | ||
| o[f] = o[member][f].bind(o[member]); | ||
| } | ||
| return o; | ||
| } | ||
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| module.exports = EventEmitter2; |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,63 @@ | ||
| var should = require('should'); | ||
| var EE = require('../lib/events.js'); | ||
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| describe('Test events', function() { | ||
| it('should create an EventEmitter2', function(done) { | ||
| var ev = EE.create(); | ||
| should(ev).be.an.Object(ev); | ||
| done(); | ||
| }); | ||
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| it('should trigger an event', function(done) { | ||
| var ev = EE.create(); | ||
| ev.on('event1', function(param) { | ||
| done(); | ||
| }); | ||
| ev.trigger('event1'); | ||
| }); | ||
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| it('should trigger two differnt events defined as a comma separated string', function(done) { | ||
| var ev = EE.create(); | ||
| var eventsLeft = 2; | ||
| ev.on('event2,event3', function(param) { | ||
| eventsLeft--; | ||
| should(param).be.equalOneOf([11, 12]); | ||
| if (eventsLeft == 0) done(); | ||
| }); | ||
| ev.trigger('event2', [11]); | ||
| ev.trigger('event3', [12]); | ||
| }); | ||
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| it('should trigger two differnt events defined as an array', function(done) { | ||
| var ev = EE.create(); | ||
| var eventsLeft = 2; | ||
| ev.on(['event4', 'event5'], function(param) { | ||
| eventsLeft--; | ||
| should(param).be.equalOneOf([21, 22]); | ||
| if (eventsLeft == 0) done(); | ||
| }); | ||
| ev.trigger('event5', [22]); | ||
| ev.trigger('event4', [21]); | ||
| }); | ||
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| it('should extend an object', function(done) { | ||
| var MyObject = function() { | ||
| EE.extendObject(this, EE.create()); | ||
| }; | ||
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| var myObject = new MyObject(); | ||
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| should(myObject).have.ownProperty('_EE'); | ||
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| var eventsLeft = 2; | ||
| myObject.on(['event6', 'event7'], function(param) { | ||
| eventsLeft--; | ||
| should(param).be.equalOneOf([25, 26]); | ||
| if (eventsLeft == 0) done(); | ||
| }); | ||
| // Trigger on the main object | ||
| myObject.trigger('event6', [25]); | ||
| // Trigger on the EventEmitter member | ||
| myObject._EE.trigger('event7', [26]); | ||
| }); | ||
| }); |