Subj : [Fwd: Re: Rhino help]
To   : netscape.public.mozilla.jseng
From : Igor Bukanov <igor@fastmail.fm>
Date : Fri Jul 25 2003 08:14 pm


Prasad Sethumadhavan wrote:
> i have the following javascript
> methods to be implemented 
> queue()  and queue("text value").
> The java class implementing it looks this:
> 
> public class PromptScriptableObject extends ScriptableObject {
>   //other required methods like getClassName() etc...
>     public void jsFunction_Queue() throws Exception {
>         LOGGER.debug(module + "Prompt.Queue()");
>     }
>     public void jsFunction_Queue(String strText) throws Exception {
>         LOGGER.debug(module + "Prompt.Queue(" + strText + ")");
>     }
>    }
> However the rhino runtime doesn't call the correct functions (i am expecting
> that it will do this automatically). However i saw you following message and
> i guess you are saying that we need to handle this ourselves.
> If you would need to support only a version of document.write with a 
> single argument, you would use jsFunction_write(String str), Rhino will 
> convert the corresponding JavaScript argument automatically when calling 
> it. But since you need to deal with JS calling document.write(arg1, 
> arg2, ...(, you should use something like:
> 
> void jsFunction_write(ScriptableObject str)
> public static Object jsFunction_getClass(
>  Context cx,Scriptable thisObj, Object[] args, Function funObj)
> {
>  StringBuffer sb = new StringBuffer();
>  for (int i = 0; i != args.length; ++i) {
>   sb.append(ScriptRuntme.toString(args[i]));
>  }
>  DocumentClass doc = (DocumentClass)thisObj;
>  doc.write_impl(sb.toString());
>  return Undefined.instance; // void result
> }
> However i don't quite understand the code snippet totally. It would be great
> if you could help me out in this.

Rhino does not support overloading when you extend ScriptableObject to
implement a custom host object. If you need this functionality, you have
to declare a single static method jsFunction_<js-function-name> with
signature

public static Object jsFunction_<js-function-name>(
	Context cx, Scriptable thisObj, Object[] args, Function funObj)
{
....
}

and explicitly check for length of args array and convert arg elemnts to
a Java type using ScriptRuntime.toSomething functions.

In your case you will have something like:

public static Object jsFunction_Object(
	Context cx, Scriptable thisObj, Object[] args, Function funObj)
	throws Exception
{
	if (!(thisObj instanceof PromptScriptableObject))
		throw Context.reportRuntimeError("Incompatible call");
	PromptScriptableObject self = (PromptScriptableObject)thisObj;
	if (args.length == 0) {
		LOGGER.debug(self.module + "Prompt.Queue()");
	} else {
		String strText = ScriptRuntime.toString(args[0]);
		LOGGER.debug(module + "Prompt.Queue(" + strText + ")");
	}
	return Undefined.instance;	
}

Regards, Igor

.