Subj : [Q] Parent objects, prototypes, inheritance and JS_InitClass...
To   : netscape.public.mozilla.jseng
From : "t o b e" <Toby.Bradshaw@NOSPAMoregan.net>
Date : Wed Nov 19 2003 08:36 pm

Please help me with my understanding and correct me where I'm wrong:

==

Inheritance in Javascript is expressed through a chain of prototype objects.
Each call to JS_InitClass takes an argument which is the prototype of the
superclass and returns the prototype to the new class which is then passed
to either JS_NewObject or JS_DefineObject to create an actual instance of
the class.

==

Given this I've got the following questions:

In JS_InitClass, what exactly is the second argument 'obj' used for. I seem
to get decent results passing almost any JSObject in except NULL.. The API
doc simply says 'Pointer to the object to use for initializing the class'.
Eh ? Initializing in what way ? And why is it necessary to provide the
property and function specs for the parent prototype in this situation ?

Why do JS_DefineObject and JS_NewObject take arguments to both a JSClass and
a prototype. ? Is the class argument completely redundant when an existing
prototype is available ? Also.. what exactly is the 'parent' argument to
these calls for. Can anyone define what 'parent' means in this context ??

I also don't have a clue what 'constructors' are for.. apart form
initializing members, of course.. the docs suggest they allow you to specify
static functions and properties for JSObjects but what this means precisely
in a Javascript context I'm not sure...

And lastly.. but by no means least.. are there any better
guides/explanations to embedding Javascript than the rather cursory ones
available on the mozilla website  ? Any books you'd recommend ?

Any help *very* gratefully received.. thanks in advance..

Toby Bradshaw
Senior Engineer,
Oregan Networks,
London, UK.

If you're replying directly please remove the NOSPAM in my e-mail address.

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