Subj : Re: [spidermonkey] getter/setter for all properties of an object
To   : netscape.public.mozilla.jseng
From : Brendan Eich
Date : Wed Aug 17 2005 09:54 pm

franck wrote:

> 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 )


The name is not stored in the object, it's shared in a type-inference 
tree in the JSRuntime.  Don't worry about its overhead unless you can 
prove it matters.


> 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 ?


No.  First, the integer property ids that fit in a jsval (or jsid) are 
stored as tagged integers, not as strings.  Second that big runtime-wide 
lexicographic tree I mentioned above is where properties are stored. 
The object owns a hash table of pointers into that structure, which is 
much smaller.

/be

.