Signal.js

/*
Script: Signal.js
	Makes chaining functions easy!
	
License & Copyright:
	Copyright 2009, Mark Obcena <keetology.com>
	MIT-Style License
*/

(function(global){

this.Signal = new Class({
	
	obj: global,
	fn: $empty,
	fnName: '$empty',
	preStack: [],
	postStack: [],

	initialize: function(fn, obj){
		obj = this.obj = obj || global;
		if (typeof fn !== 'string'
			&& !(obj[fn] instanceof Function)) throw new Error("No such function");
		this.fnName = fn;
		this.fn = obj[fn];
		this.attach();
	},
	
	attach: function(){
		var self = this;
		this.obj[this.fnName] = function(){
			for (var x = 0, y = self.preStack.length; x < y; x++){
				var item = self.preStack[x];
				item.obj[item.fn].apply(item.obj, arguments);
			}
			var result = self.fn.apply(self.obj, arguments);
			for (var x = 0, y = self.postStack.length; x < y; x++){
				var item = self.postStack[x];
				item.obj[item.fn].apply(item.obj, arguments);
			}
			return result;
		};
	},
	
	detach: function(){
		this.obj[this.fnName] = this.fn;
	},
	
	connect: function(fn, obj, before){
		obj = obj || global;
		if (typeof fn !== 'string' && !(obj[fn] instanceof Function)) return;
		this[before ? 'preStack' : 'postStack'].push({
			obj: obj,
			fn: fn
		});
		return this;
	},
	
	disconnect: function(fn, obj, before){
		obj = obj || global;
		var stack = before ? 'preStack' : 'postStack';
		this[stack] = this[stack].filter(function(item){
			return !(item.obj === obj && item.fn === fn);
		});
		return this;
	}

});

})(this);

signal_usage.js

// Globals

var woot = function(msg){
	console.log('Woot! ' + msg);
};

var yay = function(msg){
	console.log('Yay! ' + msg);
};

var mySignal = new Signal('woot');
mySignal.connect('yay');
woot('test');
// Woot! test
// Yay! test

mySignal.disconnect('yay');
woot('test');
// Woot! test


// Methods

var A = {
	woot: function(msg){
		console.log('Woot! ' + msg);
	}
};

var B = {
	yay: function(msg){
		console.log('Yay! ' + msg);
	}
};

var mySignal = new Signal('woot', A);
mySignal.connect('yay', B);
A.woot('test');
// Woot! test
// Yay! test

mySignal.disconnect('yay', B);
A.woot('test');
// Woot! test