Subj : Re: [spidermonkey] getter/setter for all properties of an object
To   : netscape.public.mozilla.jseng
From : franck
Date : Wed Aug 17 2005 04:26 pm

Brendan Eich wrote:
> franck wrote:
> 
>> Hello,
>>
>> I am tring to make a little object that allows me to listen all 
>> properties get and set of an object ( a kind of super watch ).
>> All is working properly, however I noticed that even if I defined my 
>> own setProperty, the property is stored in the object ( I can see it 
>> using a for-in loop ).
> 
> 
> 
> If you don't want a property to be enumerated by a for-in loop, you must 
> define it without the JSPROP_ENUMERATE attribute.  In your example, you 
> set obj.foo = 1234, which makes an enumerable property, per ECMA-262. 
> You would have to add a resolve hook that defines the property id being 
> resolved with 0 attributes to avoid this.
> 
> If you want to avoid storing the last-got or last-set value in a slot 
> (the normal storage for a property value, allocated by default), you 
> would want to use JSPROP_SHARED as the attributes when resolving.
> 
> If you wish to resolve only when the id is being assigned to, you want 
> JSCLASS_NEW_RESOLVE, and in your JSNewResolveOp, define that id only if 
> JSRESOLVE_ASSIGNING.
> 
> /be


Thanks for your help Brendan.
Now I'm using JSCLASS_SHARE_ALL_PROPERTIES in the JSClass flags, and I defined an ( empty ) newEnumerate hook to avoid for-each to detect anything.

If I understood, there is no way to avoid the property name to be stored in the object ( JSPROP_SHARED is only for the value )

var obj = new ObjectEx()
for ( var i=0; i<100000; i++ )
   obj[i] = some_datas;

This will create 100000 strings ( the name of the properties '0'...'99999' ) in the object ?

.