How about separate call backs at the class level? That would solve my
problem with minimal code movement. Something like:
JSClassSetPropertyGetterSetter(ctx,class,"red",myRedGetter,myRedSetter);
Would that be more within the design?
BTW, thanks for listening and leading me through some things. I'm
basically just asking for an API to save me trouble (though other
engines have it, so it's not outside the realm) -- and you guys paying
attention and talking me through things I don't know is very helpful.
[>] Brian
On Jul 20, 2009, at 4:27 PM, Geoffrey Garen wrote:
I'm not sure you get exactly what I'm saying as you put class in
places where I'd expect property. For instance:
"
I looked briefly, and it seems like it would be relatively easy to
add an API for adding C getters and setters to a class
individually. So, that seems like a reasonable feature request. "
Replacing class with property is what I'd expect here, i.e., each
property set on an object has it's own getter and setter.
Something like:
void
JSObjectSetPropertyWithCallback
(ctx
,object
,propertyName
,value,getterFunction,setterFunction,attributres,exception);
What I was referring to when talking about classes was that
JavaScriptCore has an API for defining classes, and an API for
making JavaScript objects that instantiate those classes. Currently,
that's how the API accommodates C getters and setters.
Also I'm a little worried about the word "dynamic", these are
definitely static. I have all the functions created, you just have
a pointer to them. If the pointer exist, call it for the value and
break out. If it doesn't, go down the chain.
What I meant by "dynamic" was that getters and setters that are not
pre-defined as a part of a class are dynamically added to objects in
an ad hoc manner, thereby defeating many optimizations in the object
system.
It would be trivial for the object system to efficiently handle the
instruction "add this getter / setter to all objects of this class."
It would be challenging, and require substantial design thinking,
for the object system to efficiently handle thousands of instances
of the instruction "add this getter / setter to this object."
1) I don't need to define classes for objects; right now, the only
reason I would need to create classes (instead of just passing
NULL) is to setup the getters & setters. This reduces workload and
generalizes a lot of my code
Indeed, it's a bit more code to create a class, add getters and
setters to it, and then create an object with that class, than it
would be to add getters and setters directly to an object. But I
don't think it's a prohibitive increase in code -- do you?
2) The JS engine has already looked up the property by name; with
class based getters/setters, I also have to lookup the property by
name. With property based getters/setters, it's only looked up
once and directly called to me. This should be a big savings win
and should be more simple at the back end (if there's no getter/
setter associated with a property, just skip forward down the chain.)
I don't understand the optimization you're describing here, but I
can tell that, given the current design of JavaScriptCore, classes
are more efficient than ad hoc properties.
Geoff
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