More fun with scopes and ScriptObjectMirror

[Tim Fox]

Attila-

Perhaps a more fundamental question is, is what I am trying to do 
(implement commonJS require) really possible in Vanilla Nashorn?

I did notice this post by you in December 2012:

http://mail.openjdk.java.net/pipermail/nashorn-dev/2012-December/000014.html

I understand there is no intention to implement require() directly in 
Nashorn, but my previous understanding was that it should be possible to 
implement it myself on top of Nashorn given that I can create different 
scopes and pass JS objects between them. After my recent experiments I'm 
not sure that understanding is really correct!

What's your view on this?




On 10/12/13 19:49, Tim Fox wrote:
> Sorry for the deluge of posts, but I think I've found another issue 
> with scopes/ScriptObjectMirror.
>
> Consider this case: https://gist.github.com/purplefox/7896892
>
> I have a simple JS object which contains a function 'setCallback' 
> which simply delegates to a Java object which also has a setCallback 
> method.
>
> Calling this method works fine from within the same scope that it was 
> created in.
>
> However, if I export the object to another scope - wrapping in 
> ScriptObjectMirror as advised (and this is exactly the kind of thing I 
> would need to do to implement CommonJS require in Nashorn), and then 
> try to call the setCallback method from there, it yields the following 
> exception:
>
> java.lang.ClassCastException: Cannot cast 
> jdk.nashorn.api.scripting.ScriptObjectMirror to java.lang.Runnable
>     at 
> sun.invoke.util.ValueConversions.newClassCastException(ValueConversions.java:461)
>     at 
> sun.invoke.util.ValueConversions.castReference(ValueConversions.java:456)
>     at jdk.nashorn.internal.scripts.Script$\^eval\_._L2(<eval>:3)
>     at 
> jdk.nashorn.internal.runtime.ScriptFunctionData.invoke(ScriptFunctionData.java:500)
>     at 
> jdk.nashorn.internal.runtime.ScriptFunction.invoke(ScriptFunction.java:207)
>     at 
> jdk.nashorn.internal.runtime.ScriptRuntime.apply(ScriptRuntime.java:378)
>     at 
> jdk.nashorn.api.scripting.ScriptObjectMirror.call(ScriptObjectMirror.java:107)
>     at jdk.nashorn.internal.scripts.Script$\^eval\_.runScript(<eval>:1)
>     at 
> jdk.nashorn.internal.runtime.ScriptFunctionData.invoke(ScriptFunctionData.java:498)
>     at 
> jdk.nashorn.internal.runtime.ScriptFunction.invoke(ScriptFunction.java:207)
>     at 
> jdk.nashorn.internal.runtime.ScriptRuntime.apply(ScriptRuntime.java:378)
>     at 
> jdk.nashorn.api.scripting.NashornScriptEngine.evalImpl(NashornScriptEngine.java:544)
>     at 
> jdk.nashorn.api.scripting.NashornScriptEngine.evalImpl(NashornScriptEngine.java:526)
>     at 
> jdk.nashorn.api.scripting.NashornScriptEngine.evalImpl(NashornScriptEngine.java:522)
>     at 
> jdk.nashorn.api.scripting.NashornScriptEngine.eval(NashornScriptEngine.java:193)
>     at 
> org.vertx.java.platform.impl.HandlerScopeTest.run(HandlerScopeTest.java:48)
>     at 
> org.vertx.java.platform.impl.HandlerScopeTest.main(HandlerScopeTest.java:9)
>     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
>     at 
> sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
>     at 
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
>     at java.lang.reflect.Method.invoke(Method.java:483)
>     at 
> com.intellij.rt.execution.application.AppMain.main(AppMain.java:120)
>