Signals allow an event to be dispatched to listening slots, without using a global object and without using strings for event names. For more information, see js-signals, which this is mostly based on. Typically, signals are named in the past tense, and can pass arbitrary arguments to the listening slots.
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Signals in JS
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| function( | |
| a, // placeholder | |
| b, // placeholder | |
| c // placeholder | |
| ){ | |
| return { // return an object | |
| s: a = [] // s stands for 'slots', initialize a to empty array (slots) | |
| ,d: function(){ // d stands for 'dispatch', and accepts an arbitrary number of args | |
| for( | |
| c = a.slice(); // copy the array of slots | |
| b = c.pop(); // loop until c.pop() returns undefined, unfortunately in reverse order | |
| ) | |
| b.apply(this,arguments) // b is a slot, apply the args | |
| } | |
| ,r: function(c){ // r stands for 'remove', accepts a single slot (function) to remove | |
| a.splice( // splice the list of slots | |
| a.indexOf(c), // matching the passed slot's index | |
| 1) // and remove that element | |
| } | |
| } | |
| } |
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| function(a,b,c){return{s:a=[],d:function(){for(c=a.slice();b=c.pop();)b.apply(this,arguments)},r:function(c){a.splice(a.indexOf(c),1)}}} |
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| DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE | |
| Version 2, December 2004 | |
| Copyright (C) 2011 Andrew Petersen <http://kirbysayshi.github.com> | |
| Everyone is permitted to copy and distribute verbatim or modified | |
| copies of this license document, and changing it is allowed as long | |
| as the name is changed. | |
| DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE | |
| TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION | |
| 0. You just DO WHAT THE FUCK YOU WANT TO. |
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| { | |
| "name": "signal", | |
| "description": "A signal, for named event properties", | |
| "keywords": [ | |
| "signal", | |
| "event", | |
| "emitter", | |
| "slot" | |
| ] | |
| } |
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| <!DOCTYPE html> | |
| <title>Foo</title> | |
| <div>Expected value: <b><br />what it was: bigfoot sasquatch [object Window]<br/>what it was bigfoot [object Object]</b></div> | |
| <div>Actual value: <br /><b id="ret"></b></div> | |
| <script> | |
| var Signal = function(a,b,c){return{s:a=[],d:function(){for(c=a.slice();b=c.pop();)b.apply(this,arguments)},r:function(c){a.splice(a.indexOf(b),1)}}} | |
| var Something = function(){ | |
| this.wasHere = Signal(); | |
| this.move = function(){ | |
| this.wasHere.d('bigfoot', 'sasquatch'); // d for dispatch! | |
| } | |
| } | |
| // a slot is just a callback | |
| ,what = function(wasIt){ | |
| // 'this' will be the signal obj itself | |
| document.getElementById( "ret" ).innerHTML | |
| += 'what it was: ' | |
| + wasIt + ' ' + this + '<br />'; | |
| } | |
| ,scope = (function(wasIt, sas){ | |
| // 'this' will be the global obj | |
| document.getElementById( "ret" ).innerHTML | |
| += 'what it was: ' | |
| + wasIt + ' ' + sas + ' ' + this + '<br />'; | |
| }).bind(this) | |
| var s = new Something(); | |
| s.wasHere.s.push(what); // add 'what' as a slot in the wasHere signal | |
| s.wasHere.s.push(scope); // add 'scope' as a slot in the wasHere signal | |
| s.move(); // this signals the slots in reverse order | |
| </script> |
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