Possible scope leak in Nashorn

Tim Fox timvolpe at gmail.com
Tue Dec 10 09:15:04 PST 2013

On 10/12/13 16:52, André Bargull wrote:
>> Thanks, I adapted the code to use ScriptUtils.wrap() and encountered a
>> strange situation where JSON.stringify returns undefined for a valid JS
>> object. Maybe another scope problem?
>> Here is a reproducer:https://gist.github.com/purplefox/7893408
> No, it's not a  scope problem. JSON.stringify isn't able to process 
> ScriptObjectMirror objects, see ll. 263-270 in NativeJSON.java [1].
> - André
> [1] 
> http://hg.openjdk.java.net/nashorn/jdk8/nashorn/file/tip/src/jdk/nashorn/internal/objects/NativeJSON.java

I see, so when a JS method in one scope is invoked from another scope 
all the arguments get automatically wrapped in a ScriptObjectMirror. I 
suppose NativeJSON needs to check for ScriptObjectMirror and unwrap 
internally before attempting to stringify (?)

I wonder if anyone could suggest a workaround for now? (it's not obvious 
to me)

Regarding the wrapping - do you think the argument wrapping is going to 
impose a significant performance penalty? I'm thinking of CommonJS based 
systems like node or vert.x (JS) where you are calling between scopes 
basically every time you call the api.


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