Subj : Re: RHino newbie: getter not working
To   : Brian J. Sayatovic
From : Igor Bukanov
Date : Tue Jan 18 2005 12:08 pm

Brian J. Sayatovic wrote:
> I wrote a simple Java class hierarchy...
> 
>    ScriptableObject-->MyObject-->MyNode-->MyView-->MyCanvas
> 
> The final class has this in it:
> 
>    public String jsGet_build() {
>        return "2";
>    }
> 
> I then have a script that looks like this:
> 
>    var canvas = new Packages.org.trinition.mytest.MyCanvas();
>    canvas; // or canvas.build;
> 
> When I execute this script, I use the following:
> 
>            String filename2 = "Test Data/test1.js";
>            FileReader reader = new FileReader(filename2);
>                      Object result = context.evaluateReader(scope, 
> reader, filename2, 1, null);
>                      System.out.println("Result: " + result);
> 
> The return value for "canvas;" is:
> 
>    Result: org.trinition.mytest.MyCanvas@13ad085
> 
> However, when I use "canvas.build;", I get:
> 
>    Result: org.mozilla.javascript.Undefined@18e2b22
> 
> I don't understand why my getter isn't working.  What am I doing wrong?

To make getters in classes extending from ScriptableObject to work you 
have to call ScriptableObject.defineClass(scope, yourClass). It will 
prepare your class instances to behave as standard ECMAScript objects. 
For example, assuming that MyCanvas contains:

public String getClassName() { return "MyCanvas"; }

after ScriptableObject.defineClass(scope, MyCanvas.class) the scope 
would contain MyCanvas constructor that you can use to create instances 
of MyCanvas. As with the standard objects like Date or Array you will 
get MyCanvas.prototype which scripts can populate with additional 
functions like with any other Constructor.prototype cases. 
MyCanvas.prototype also contains objects wrapping getters and setters 
and that is why without calling defineClass they do not work.

Regards, Igor

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