On Jun 12, 2014, at 12:25 PM, Boris Zbarsky wrote:

> On 6/12/14, 3:21 PM, Allen Wirfs-Brock wrote:
>> simply not knowing whether all of the DOM [[Construct]] semantics could be successfully replaced replaced using only @@create methods and constructor bodies.
> 
> WebIDL currently doesn't use a custom [[Construct]] at all.  It uses a custom [[Call]] on DOM constructors.

Is the custom [[Call]] only use to implement WebIDL overload/argument processing semantics?  Or do you perform object allocations within the [[Call].  Have you looked at how such constructors would behave when a subclass constructor does a super call to them?

> 
> Chances are, we want to move from that to using @@create or whatever is needed to allow subclassing.  In either case, I don't think we'll be doing custom [[Construct]] in the DOM.

When we talked about this in TC29 I don't think anybody identified any specific cases where they knew it would be an issue.  The hesitation was more about uncertainty concern the unknown. 

Allen

On Jun 12, 2014, at 12:25 PM, Boris Zbarsky wrote:

> WebIDL currently doesn't use a custom [[Construct]] at all.  It uses a custom [[Call]] on DOM constructors.

Is the custom [[Call]] only use to implement WebIDL overload/argument processing semantics?  Or do you perform object allocations within the [[Call].  Have you looked at how such constructors would behave when a subclass constructor does a super call to them?

> Chances are, we want to move from that to using @@create or whatever is needed to allow subclassing.  In either case, I don't think we'll be doing custom [[Construct]] in the DOM.

When we talked about this in TC29 I don't think anybody identified any specific cases where they knew it would be an issue.  The hesitation was more about uncertainty concern the unknown.