Subj : Re: Recalculating scope chain (i.e., 'with' statement).
To   : Christopher M. Balz
From : Brendan Eich
Date : Sat May 28 2005 03:26 am

Christopher M. Balz wrote:
> It is said in books of lore that using the 'with'
> statement is computationally expensive.  But why is
> this so, if the scope chain is merely a chain of
> object references?  Would not using the 'with'
> statement merely amount to changing about two
> references (that of the child scope, and that of the
> parent scope)?


Entering and leaving the statement governed by with is not expensive. 
It's the name lookups inside the with.  They must be made at runtime; 
you cannot optimize a name get or set within a with statement to a stack 
frame slot for all identifiers that match formal argument and declared 
local variable names.


> Separately, are there any plans to open up access to a
> function closure via object references?


No.  Why do you want to capture the activation object (SpiderMonkey's 
internal class for this is named Call), exactly?

/be

.