There is no notion of wrap/unwrap of user implemented JSObject - so
those won't be affected. JSObject itself is just another Java type and
so would be between script and Java code "as is".
Only for Object param types of Java methods will receive wrapped
ScriptObjects - argument filter will be inserted for such parameters.
Actually a filter is already installed for such params to handle
ConsString objects - so ScriptObject wrapping is just another
incremental check+wrap in that filter. And Object returning Java methods
will have unwrapper filter on return value (on the script side). Other
Java parameter types/return type should not be affected at all.
Providing another command line option implies we keep checking it in
argument/return type filter methods - which would be costly.
-Sundar
On Friday 17 October 2014 09:23 AM, Serguei Mourachov wrote:
Sundar
Will it also affect classes implementing JSObject?
IMO, we should have an option to disable this wrap/unwrap behavior in
cases when it significantly affecting performance.
SM
On 10/16/2014 6:44 AM, A. Sundararajan wrote:
There were many questions in this list and elsewhere on
ScriptObjectMirror. This email is to clarify those.
Nashorn represents JavaScript objects as instances of implementation
class called jdk.nashorn.internal.runtime.ScriptObject or one of it's
subclasses (like NativeArray, NativeRegExp etc. - or even generated
ones like jdk.nashorn.internal.scripts.JO4 etc)
When ScriptObjects are returned from a script function or evaluated
script code, ScriptEngine.eval returns an instanceof
jdk.nashorn.api.scripting.ScriptObjectMirror.
http://cr.openjdk.java.net/~sundar/jdk.nashorn.api/9/javadoc/jdk/nashorn/api/scripting/ScriptObjectMirror.html
Example:
ScriptEngine e = new
ScriptEngineManager().getEngineByName("nashorn");
Object obj = e.eval("var obj = { foo: 23 }"); // obj is an
instance of ScriptObjectMirror
Caller can cast the result to ScriptObjectMirror to access properties
of that script object or call methods on it. All javax.script
interface methods returning Object (ScriptEngine.eval,
Invocable.invokeFunction, Invocable.invokeMethod) return
ScriptObjectMirror if underlying script or script function/method
returns a JS object.
But, if you call any Java method accepting Object type param or
assign to element of Object[], then Nashorn was not wrapping
ScriptObject in the past. i.e., 'raw' ScriptObject (or subclass)
instances "escaped" to Java layer. If you try to cast those to
ScriptObjectMirror from Java code, you got ClassCastException. Also,
if you passed such raw object as "self" parameter for
Invocable.invokeMethod, you would IllegalArgumentException. This was
causing a lot of confusion - script objects got to java code
sometimes as wrapped mirror objects and sometimes as 'raw' objects!
With a recent change
http://hg.openjdk.java.net/jdk9/dev/nashorn/rev/a8d44c7c2ac0
in jdk9 and the corresponding backport to jdk8u-dev
http://hg.openjdk.java.net/jdk8u/jdk8u-dev/nashorn/rev/a35c8136c045
the way nashorn wraps internal ScriptObjects to ScriptObjectMirror
has changed. Script objects are always wrapped to ScriptObjectMirror
- even when you're calling Java method that accepts "Object" type
value. Also, return values from java methods returning Object are
"unwrapped" (if the return value is a ScriptObjectMirror) when it
gets to script execution.
Example:
// list gets ScriptObjectMirror as element
engine.eval("var m = new java.util.HashMap(); l.put('myobj', {
foo: 33 });");
engine.eval("var obj = m.get('myobj'); // obj gets unwrapped as
ScriptObject here");
With this change, raw ScriptObjects don't escape to Java layer at all.
Hope this helps,
-Sundar
