Javascript/OpenSource question

[Fusengammu]

Hi, one day a long time ago (3 yrs), I was working on Javascript where I really wanted to be able to use Java/C++ style inheritance instead of the built in prototype inheritance, so I came up with a scheme to do this. Now I'm working on some ActionScript in Flash and needed this facility yet again. So, I once again recoded my inheriance hack yet again in ActionScript.

No, I'm not having trouble making it work, but I was wondering if anyone has ever heard or seen of making JavaScript's OO behave like Java's OO. If not, I would like to opensource this method, but don't exactly know where to begin.


It works like this:

File oo.js:
/*
3/14/2003 by Kensuke Arai araikensuke@hotmail.com
original code, from sometime in the year 2000
*/

function OOEvolve(subclass)
{
for( key in subclass.superClass )
{
if( subclass.superClass[key] != null )
{
subclass[key] = subclass.superClass[key];
}
}

// native code doesn't get copied over, so...
sSuperToStringCode = subclass.superClass.toString + "";
sSubToStringCode = subclass.toString + "";

if( (sSuperToStringCode.indexOf("[native code]") < 0) &&
(sSubToStringCode.indexOf("[native code]") >= 0) )
{
subclass.toString = subclass.superClass.toString;
}
}



File OOTest.html:

/***********************/
// MUST INCLUDE using SCRIPT src="oo.js"
/***********************/


// SUPERCLASS Vehicle
function Vehicle(sManufacturer, iWheels, iWeight)
{
this.sManufacturer = sManufacturer;
this.iWheels = iWheels;
this.iWeight = iWeight;

this.toString = Vehicle_toString;
}

function Vehicle_toString()
{
return "Object type vehicle. Manufactured by " + this.sManufacturer +
", has " + this.iWheels + " wheels, and weighs " + this.iWeight;
}







// SUBCLASS
// A type of car. It can be outfitted in several different
// trim levels.
function AustinMini(sTrimLevel)
{
// DECLARE WHAT SUPERCLASS I EXTEND
this.superClass = new Vehicle("Austin", 4, 1700);
OOEvolve(this);

// overloaded toString for AustinMini...
this.sTrimLevel = sTrimLevel;
this.toString = AustinMini_toString;
}

function AustinMini_toString()
{
return "Object type AustinMini. Manufactured by " + this.sManufacturer +
", has " + this.iWheels + " wheels, and weighs " + this.iWeight +
". The trim level is " + this.sTrimLevel;
}







// SUBCLASS
// A type of bicycle. Bicycles come in sizes.
function CannondaleR2000(iSize)
{
// DECLARE WHAT SUPERCLASS I EXTEND
this.superClass = new Vehicle("Cannondale", 2, 16);
OOEvolve(this);

this.iSize = iSize;

this.getSize = Cannondale_getSize;
}

function Cannondale_getSize()
{
return this.iSize;
}


var minicooper = new AustinMini("Cooper");
var stdcooper = new AustinMini("S");
var cannondale = new CannondaleR2000();

alert(minicooper.toString());
alert(stdcooper.toString());
alert(cannondale.toString());

 

[binaryDigit]

Don't know if it exists or not, but to "open source" it you just have to specify the license agreement in the header of your file(s). So if you want to use GPL/LGPL, you state so in your header files. You might want to check out what other requirements those license agreements might have (like including a copy of the LA in complete with your source). If you are going with a BSD type license, then the procedure is the same, you state it in the header of any source files. You are of course free to specify any whatever license you choose since "open source" means different things to different people.