> -----Original Message-----
> From: Kris Zyp [mailto:[EMAIL PROTECTED]
> Sent: 13. mars 2008 11:27
> To: Lars Hansen; [email protected]
> Subject: Re: Controlling DontEnum (was: ES4 draft: Object)
>
> > the frequency of use). Thus on Object.prototype and as an
> intrinsic
> > propety on Object instances:
> >
> > function __createProperty__(name:EnumerableId,
> > dontEnum:boolean=false,
> > dontDelete:boolean=false,
> > readOnly:boolean=false): void
> I thought that this only made sense in conjunction with
> Neil's suggestion of providing the value at the same time. If
> you create a readonly property, how are you supposed to set
> the value otherwise? Shouldn't it be:
> function __createProperty__(name:EnumerableId,
> value,
> dontEnum:boolean=false,
> dontDelete:boolean=false,
> readOnly:boolean=false): void
Simple oversight. You are right.
> And if readOnly implied dontDelete, I would have guessed
> readOnly to be a little more frequent than dontDelete, but of
> course that is just a guess.
ReadOnly implies DontDelete because ReadOnly doesn't make sense without
DontDelete, but my guess (based on no data at all, just how I write
code) is that undeletable mutable state is desired slightly more often
than undeletable immutable state. (Also, if you're asking for
ReadOnly=true then you're forced to state DontDelete=true, reminding you
of this fact. My hunch is that this order slightly reduces the scope
for error, which would be greater if you could state ReadOnly=true
without being forced to think about DontDelete in the last argument
position.)
All that said, I like Yuh-Ruey Chen's variation, where flags are tokens
extracted from Object but passed individually following the value; if we
ever end up with strong type checks for rest arguments (a feature that
is a little wobbly at present) then the API would look like this:
class Object {
static const READ_ONLY : AttrToken = new AttrToken;
static const DONT_ENUM : AttrToken = new AttrToken;
static const DONT_DELETE : AttrToken = new AttrToken;
intrinsic function __createProperty__(name, value, ...bits :
[AttrToken]) ...
}
for some opaque non-user-accessible class AttrToken.
--lars
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