Norris Boyd wrote:
> On Sep 13, 8:22 pm, wolffiex <[EMAIL PROTECTED]> wrote:
>> Hi everyone,
>> I found a little surprising behavior today with Rhino. I don't know if
>> this is a bug; I'm hoping someone will weigh in. It appears that
>> instanceof doesn't work on objects from a foreign scope. I assume this
>> is because instanceof just looks up the prototype chain, but I wonder
>> if that is the correct implementation, given the fact that you can
>> pass objects from one scope to another using Rhino and Java. Here's my
>> little testcase:
>>
>> import org.junit.Test;
>> import org.mozilla.javascript.ContextFactory;
>> import org.mozilla.javascript.Context;
>> import org.mozilla.javascript.Scriptable;
>> import org.mozilla.javascript.ScriptableObject;
>>
>> public class ObjectSurprise {
>> @Test
>> public void showBug(){
>> ContextFactory factory = new ContextFactory();
>> Context cx1 = factory.enterContext();
>> Context cx2 = factory.enterContext();
>> final Scriptable scope1 = cx1.initStandardObjects();
>>
>> cx1.evaluateString(scope1,
>> "tryMe = function(){return {};}",
>> "tryMe", 1, null);
>>
>> Scriptable result = (Scriptable)
>> ScriptableObject.callMethod(scope1, "tryMe", new Object[]
>> {});
>>
>> String throwIfNotObject =
>> "isObject = function(obj){ if( !(obj instanceof
>> Object)) throw('not an object');}";
>>
>> cx1.evaluateString(scope1, throwIfNotObject, "isObject", 1,
>> null);
>> Object [] arg = { result };
>>
>> //doesn't throw, as expected
>> ScriptableObject.callMethod(scope1, "isObject", arg);
>> Context.exit();
>>
>> final Scriptable scope2 = cx2.initStandardObjects();
>> cx2.evaluateString(scope2, throwIfNotObject, "isObject", 1,
>> null);
>>
>> //throws -- unexpected
>> ScriptableObject.callMethod(scope2, "isObject", arg);
>> Context.exit();
>> }
>>
>> }
>
> You're right: instanceof just walks up the prototype chain looking for
> the object. Mixing objects from two separate initStandardObject calls
> is problematic in general; why do you need to do this?
we didn't hurt this problem until now, but in the case of HtmlUnit,
mixing objects of two separate initStandardObject calls is natural as
each Window is a top scope and windows have access to child and parent
windows.
Cheers,
Marc.
--
Web: http://www.efficient-webtesting.com
Blog: http://mguillem.wordpress.com
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