On Sun, 18 May 2008, Maciej Stachowiak wrote:
> On May 18, 2008, at 3:18 PM, Brady Eidson wrote:
> >
> > While I'm on the topic, I'm also curious about that [XXX] placeholder.
> > There's a bug in WebKit's bugzilla pointing out that the IE8 beta and
> > Firefox 2 both support `delete storage.keyName` syntax as an alias for
> > `storage.removeItem(keyName)`
> >
> > I'm taking a guess here and assuming supporting the `delete` syntax is
> > the implied concept behind [XXX]
>
> WebKit's JavaScript engine doesn't currently have the ability to run
> custom code when a property is deleted. It would be a significant
> challenge to add this capability and possibly a performance regression;
> and no other DOM-related spec requires this, even when there is
> NameGetter or IndexGetter behavior. For example NodeLists and
> HTMLCollections do not let you delete by name to remove the item (I'm
> not sure what that would even mean). So I'd prefer not to have to
> introducethis concept just for this one case.
On Sun, 18 May 2008, Brady Eidson wrote:
>
> WebKit has the ability to add custom property deletion on a per-class
> basis - therefore not slowing down the common case at all. That's how I
> fixed the bug to make us compatible with IE8 and Firefox for now as this
> debate gets underway...
On Mon, 19 May 2008, Geoffrey Garen wrote:
>
> It is *very* weird, and therefore not a "useful shorthand."
>
> In JavaScript, "delete" means "remove this property / interface from
> this JavaScript object." I can't think of any context in which it means
> anything else.
>
> For example, "delete node.parentNode" attempts to remove the
> "parentNode" property from "node". It does not remove "parentNode" from
> the document or anything like that.
>
> "delete window" attempts to remove the "window" property from the global
> object. It does not close the window or anything like that.
>
> In other words, you can be certain that "delete" is a simple operation
> with a consistent side-effect.
>
> As a JavaScript programmer, I would find it very difficult to reason
> about objects that might or might not change the behavior of the
> "delete" operator. One reason i would find it very difficult is that
> operator overloading does not exist in JavaScript at all, so to
> understand this one API, I would need to understand a vast corpus of
> programming language goobery that is not at all covered in any
> JavaScript manual. Another reason I would find it very difficult is that
> the overloaded meaning of "delete" here ("remove persistent storage from
> disk") is far afield from the original meaning ("remove interface from
> temporary object in memory"). To give you an analogy, even in C++, where
> you're allowed to overload operator delete, if you overloaded operator
> delete to mean "do not free this object's memory, but do delete the file
> it references from the file system", well, let's just say that your
> patch would not pass code review with any of your four reviewers :).
>
> I am not sure if any JS decoration or collection libraries depend on the
> canonical behavior of operator delete, but if they do, I would hate for
> them all to have to ship with the asterisk, "BEWARE: do NOT use this
> decoration / collection library with that one weird DOM object that
> interprets 'delete' to mean 'remove important data from the user's
> disk'". Oy!
On Mon, 19 May 2008, Brady Eidson wrote:
>
> I'm unsure if you have the proper background with the Storage interface
> that is in question here. I'm guessing that the reason that Firefox 2
> and IE8 support the "modified" behavior of delete for Storage items is
> because the "way of thinking about Storage items" we're trying to get
> across meets most of the expectations of manipulating properties that
> you lay out below.
>
> On May 19, 2008, at 3:18 PM, Geoffrey Garen wrote:
> >
> > In JavaScript, "delete" means "remove this property / interface from
> > this JavaScript object." I can't think of any context in which it
> > means anything else.
>
> The spec makes it clear that storage items and properties on the Storage
> object are interchangeable.
>
> `storage.foo = "bar"` happens to be equivalent to
> `storage.setItem("foo", "bar")`, but is also no different from
> `someRandomObject.foo = "bar"` as far as keeping a collection of
> properties on an object.
>
> This also applies for enumeration, etc.
>
> Equivalently and more relevant to the discussion, `delete storage.foo`
> happens to be equivalent to `storage.removeItem("foo")`, but is also
> *little* different from `delete someRandomObject.foo`
>
> > For example, "delete node.parentNode" attempts to remove the
> > "parentNode" property from "node". It does not remove "parentNode"
> > from the document or anything like that.
> >
> > "delete window" attempts to remove the "window" property from the
> > global object. It does not close the window or anything like that.
>
> In
