On 6/18/14, 1:46 PM, Domenic Denicola wrote:
Yes, although in this case no initialization checks are necessary, just brand
checks.
Well. That depends on the desired behavior.
For example, say you have a DOMPoint as in your example above that is
supposed to return Numbers for x and y.
In your pseudocode, what happens if .x or .y is accessed after @@create
but before the constructor runs? That depends on what slot
initialization, if any, allocateNativeObjectWithSlots performs. If a
spec author wanted to not depend on implementation details like that,
they would need to define that @@create puts something in the slots
separate from whatever work the constructor does.
Note that at this point we're already forcing spec authors to think
about the exact @@create behavior to make things subclassable and that
in particular, every single existing spec that has a constructor will
need to be revisited and modified as needed.
Doing an initialization check instead of a brand check would avoid
needing to define @@create behavior in that sort of detail, I think, but
adds extra checks that need to be performed, in addition to the brand
check, and extra state (initialized or not) to be stored.
Given how few DOM objects have reasonable constructors to begin with
I'm not sure how you're defining "reasonable", but a quick look at
Gecko's IDL shows 136 IDL files that have at least constructor in them
that takes some arguments and does not simply take a single optional
argument (a dictionary, say). For comparison, we have 586 IDL files
total...
Some of these are not standards yet, and a few I think have a
no-argument constructor in addition to the one with arguments, and a
bunch are event constructors that would all presumably be defined in a
similar way in the spec, but I think you're significantly
underestimating the number of things that have constructors that
actually do something with their arguments.
-Boris
_______________________________________________
es-discuss mailing list
[email protected]
https://mail.mozilla.org/listinfo/es-discuss
