Subj : Re: spidermonkey watch on object.__count__
To   : netscape.public.mozilla.jseng
From : Jens Thiele
Date : Mon Aug 30 2004 06:11 pm

Brendan Eich wrote:
> You need more hooks than currently exist in the language itself.

yes

> You could use the jsdbgapi.h, I think.

at a first glance it seems to me to be the more complicated aproach

>> or should the above work and spidermonkey be fixed?
> Nah, __count__ should not impose costs on ordinary property addition.

it seems to me this could be done without any additional overhead if no
properties are watched (again at a first glance) - and of course it
could be done with neglectable overhead ;-)

perhaps around jsscope.c:1130

But a better solution for _my_ problem would be to have a generic watch
which calls a function whenever an object is changed (property
added/deleted/changed) - but then again perhaps I am the only one
interested in such functionality and I would have to keep a fork of
spidermonkey (which i don't want to) - please don't get me wrong I
really understand if you don't want to add this to spidermonkey.

pseudo code:

w={
	add:function(p){perhaps return true or false;}
	del:function(p){perhaps return true or false;}
	update:function(p,o,n){return new value;}
};
o={};
o.watch(w);

or perhaps watch could take three arguments
o.watch(addfunc,delfunc,upfunc);

or ...

I could try to implement something like this if there is enough interest
/ the possibility to get this into spidermonkey

jens

.