Subj : spidermonkey: reserved slot vs. private
To   : netscape.public.mozilla.jseng
From : Jens Thiele
Date : Fri Sep 17 2004 07:13 pm

Are JS_SetPrivate / JS_GetPrivate functionally "equal"
to
JS_SetReservedSlot / JS_GetReservedSlot
?

to use JS_SetPrivate / JS_GetPrivate one has to specify
JSCLASS_HAS_PRIVATE in the JSClass structure

to use JS_SetReservedSlot / JS_GetReservedSlot one has to specify
JSCLASS_HAS_RESERVED_SLOTS(xxx)

are reserved slots handled like "normal" properties?
(they are jsval's, they are garbage collected?, ...)
but hidden

=> reserved slots could sometimes be an alternative to private data

What I want to do:
i use SetPrivate/GetPrivate to store some pointer to an native object
(always making sure the class is correct)

the js object finalizer should only free the native object referenced by
the pointer if the js object owns this native object
=> i must store that ownership information somewhere
of course i could wrap the pointer and the ownership information in
another struct (or store this information somewhere completely
different) but if i could use the reserved slot to store the ownership
information this would be much simpler.

or do I get the reserved slots completely wrong?

.