72021 - The ScriptRuntime class tries to convert even the String values to JavaNativeObject

Status: VERIFIED FIXED

(Rhino Graveyard :: Core, defect)

Description

[Anup Katariya]

The rhino script engine converts every java object that the application passes
(if it is not a Scriptable object) to the JavaNativeObject. Our applaiction 
passes a String object to script runtime and it converts it to the 
NativeJavaObject. Now if the user tries to increment or decrement the string 
object in the script the runtime callls the "doubleValue" method by default to 
convert the string to number and this fails since there is no method 
named "doubleValue" implemented in the class String. 

However if the user directly declares a String object inside the script the 
script runtime recognizes it as such and deals with it correctly. 

I think the script runtime should also recognize the String object returned by 
the application that is using it. And should do the correct conversion to 
number and boolean in the same way that it does for the String objects defined 
inside the script.

Comment 1

[Igor Bukanov]

Attachment: Workaround suggestion

Comment 2

[Sam Leung]

I have come across the same problem. Below is a sample of scripts which will 
reproduce the problem when run in the Rhino shell Main:-

   a = new java.lang.String("TEST");
   a <= "TEST";

Below is a work around by changing 'a' to javascript string:-

   a = new java.lang.String("TEST");
   b = new String(a);
   b <= "TEST";

Comment 3

[Igor Bukanov]

In the current Rhino tip it is possible to convert java.lang.String returned by
Java methods directly to JS String via simple:

Context cx = Context.enter();
cx.getWrapFactory().setJavaPrimitiveWrap(false);

See API documentation for
org.mozilla.javascript.WrapFactory#isJavaPrimitiveWrap() in the current tip for
details.

Note that this does not make to work:
a = new java.lang.String("TEST");
a <= "TEST";

as WrapFactory#setJavaPrimitiveWrap(boolean) does not affect explicit
constructor calls, but if one wish to completely replace Java String, he can
override WrapFactory#wrapNewObject to return new JS String object for Java
String. See the following attachment for details.

Comment 4

[Igor Bukanov]

Attachment: WrapFactory implementation to map Java String to JS String in all cases

With this MyWrap class that example works as expected:

Rhino 1.5 release 4 0000 00 00 (in progress)
js> var  cx = Packages.org.mozilla.javascript.Context.getCurrentContext();
js> var wrap = new Packages.MyWrap(cx);
js> var a = new java.lang.String("TEST");
js> a <= "TEST";
true

Comment 5

[Igor Bukanov]

I mark the bug as fixed as the required functionality is already available with
minimal setup.

Comment 6

[Phil Schwartau]

Marking Verified. Anup, please reopen if you disagree -

Comment 7

[Igor Bukanov]

Targeting as resolved against 1.5R4