# Binder

**URL:** <https://forum.kirupa.com/t/binder/84344>\
**Category:** open source\
**Created:** [March 26, 2005, 3:59pm UTC](https://forum.kirupa.com/t/binder/84344 "2005-03-26T15:59:11Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![Voetsjoeba](https://avatars.discourse-cdn.com/v4/letter/v/ac91a4/32.png) [@Voetsjoeba](https://forum.kirupa.com/u/Voetsjoeba)\
**Post date:** [March 26, 2005, 3:59pm UTC](https://forum.kirupa.com/t/binder/84344/1 "2005-03-26T15:59:11Z")

</div>

Here’s a little class I wrote to easily bind keys to a specific function. It is a class with two static functions, **bind** and **unbind** , for obvious purposes. It takes care of the whole listener deal for you, all you need to do to bind a key to a specific function is:

```auto

Binder.bind("g", gotoAndPlay, _root, [6]);

```

That will execute \_root.gotoAndPlay(6) when you hit g. The syntax for the function to apply is the same as the Function.apply syntax:

> 

\*\*Usage:

\*\*[color=Purple] **myFunction** [/color].apply([color=Purple] **thisObject** [/color], [color=Purple] **argumentsObject** [/color]);  
\*\*  
Parameters:

**[color=Purple]thisObject[/color] The object that myFunction is applied to.[color=Purple]**

argumentsObject\*\*[/color] An array whose elements are passed to myFunction as parameters.

So in the example above, the function call would render as

```auto
gotoAndPlay.apply(_root, [6])

```

which is the same as

```auto
_root.gotoAndPlay(6);

```

Or, for any other function that takes more arguments:

```auto
theSum = sum.apply(null, [5,4,3,6,7]);

```

The sum function would then count up 5+4+3+6+7, and return the result to be stored in theSum. Because sum is a regular function and not a method, [color=Purple]\*\*thisObject \*\*[/color]is null.

Here’s the class code:

```auto

class Binder {
    
    static var count:Number = 0;
    static var objects:Array = new Array();
    
    function Binder(){
    }
    
    static function bind(key:String, applyFunction:Function, applyObject:Object, applyParams:Array) {
        
        for(var i=0;i<count;i++){
            if(objects*.hitkey == key.toLowerCase()){
                trace("Could not bind key "+key+": key already bound.");
                return false;
            }
        }
        
        var newListener = new Object();
        newListener.hitkey = key.toLowerCase();
        newListener.applyFunction = applyFunction;
        newListener.applyObject = applyObject;
        newListener.applyParams = applyParams;
        
        Key.addListener(newListener);
        
        newListener.onKeyDown = function(){
            var pressedKey:String = String.fromCharCode(Key.getCode()).toLowerCase();
            if(pressedKey == this.hitkey){
                this.applyFunction.apply(this.applyObject, this.applyParams);
            }
        }
        
        objects[count++] = newListener;
        
    }
    
    static function unbind(key:String):Void {
        
        for(var i=0;i<count;i++){
            var curListener:Object = objects*;
            if(curListener.hitkey.toLowerCase() == key.toLowerCase()){
                Key.removeListener(curListener);
                objects.splice(i,1);
                count--;
            }
        }
        
    }
    
}

```

I’ve attached the .as file 🙂