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Should callback interface objects have a "length" property? #279

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tobie opened this issue Jan 23, 2017 · 6 comments
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Should callback interface objects have a "length" property? #279

tobie opened this issue Jan 23, 2017 · 6 comments

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@tobie
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tobie commented Jan 23, 2017 •
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Callback interface objects already have a "name" property (when exposed due to the presence of constants) . The omission of a "length" prop (with value 0) in the spec seems more accidental than deliberate. Chrome, Safari and Firefox all implement it, e.g.:

NodeFilter.length;
// => 0
@tobie tobie changed the title Should callback interface objects have a "length" property Should callback interface objects have a "length" property? Jan 23, 2017
@tobie
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tobie commented Jan 23, 2017

idlharness excludes callback interfaces (with constants) from testing for the presence and value of length.

@domenic
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domenic commented Jan 23, 2017

Edge also supports this.

@domenic
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domenic commented Jan 23, 2017

A more interesting question is whether it should be an own property. NodeFilter.hasOwnProperty("length") returns true in Gecko and Blink but not Edge. (In Edge, it gets the length from NodeFilter.__proto__ === Function.prototype.)

@domenic
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domenic commented Jan 23, 2017

So I guess this amounts to changing

Interface objects for non-callback interfaces

to

All interface objects

and adding tests I suppose

@tobie
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tobie commented Jan 23, 2017

A more interesting question is whether it should be an own property. NodeFilter.hasOwnProperty("length") returns true in Gecko and Blink but not Edge. (In Edge, it gets the length from NodeFilter.proto === Function.prototype.)

For consistency with other interface objects, own prop seems more judicious.

@tobie
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tobie commented Jan 24, 2017

See also whatwg/dom#186 and #83.

tobie added a commit to tobie/webidl that referenced this issue Jan 24, 2017
@tobie
Revamp interface object bindings.
76e50d0 
* Extract legacy callback interface objects
  out of interface objects. Closes whatwg#78.
* Clarify that legacy callback interfaces are function objects.
* Give them a length property. Closes whatwg#279. Closes whatwg#83.
* Require new for Named Constructors. Closes whatwg#275.
* Rely on ES abstract operations for defining,
  named constructors, interface objects, and
  legacy callback interface objects.
* Disallow using the [NoInterfaceObject] on
  callback interfaces with constants.
tobie added a commit to tobie/webidl that referenced this issue Jan 24, 2017
@tobie
Revamp interface bindings
c04bd37 
* Extract legacy callback interface objects
  out of interface objects. Closes whatwg#78.
* Clarify that legacy callback interfaces are function objects.
* Give them a length property. Closes whatwg#279. Closes whatwg#83.
* Require new for Named Constructors. Closes whatwg#275.
* Rely on ES abstract operations for defining,
  named constructors, interface objects, and
  legacy callback interface objects.
* Disallow using the [NoInterfaceObject] on
  callback interfaces with constants.
@tobie tobie mentioned this issue Jan 24, 2017
Closed
tobie added a commit to tobie/webidl that referenced this issue Feb 14, 2017
@tobie
Revamp interface bindings
8c8c143 
* Extract legacy callback interface objects
  out of interface objects. Closes whatwg#78.
* Clarify that legacy callback interfaces are function objects.
* Give them a length property. Closes whatwg#279. Closes whatwg#83.
* Require new for Named Constructors. Closes whatwg#275.
* Rely on ES abstract operations for defining,
  named constructors, interface objects, and
  legacy callback interface objects.
* Disallow using the [NoInterfaceObject] on
  callback interfaces with constants.
tobie added a commit to tobie/webidl that referenced this issue Feb 20, 2017
@tobie
Revamp interface bindings
f3fa480 
* Extract legacy callback interface objects
  out of interface objects. Closes whatwg#78.
* Clarify that legacy callback interfaces are function objects.
* Give them a length property. Closes whatwg#279. Closes whatwg#83.
* Require new for Named Constructors. Closes whatwg#275.
* Rely on ES abstract operations for defining,
  named constructors, interface objects, and
  legacy callback interface objects.
* Disallow using the [NoInterfaceObject] on
  callback interfaces with constants.
@tobie tobie mentioned this issue Feb 20, 2017
Merged
tobie added a commit to tobie/webidl that referenced this issue Feb 20, 2017
@tobie
Revamp interface bindings
fe1e2cd 
* Extract legacy callback interface objects
  out of interface objects. Closes whatwg#78.
* Clarify that legacy callback interfaces are function objects.
* Give them a length property. Closes whatwg#279. Closes whatwg#83.
* Require new for Named Constructors. Closes whatwg#275.
* Rely on ES abstract operations for defining,
  named constructors, interface objects, and
  legacy callback interface objects.
* Disallow using the [NoInterfaceObject] on
  callback interfaces with constants.
tobie added a commit that referenced this issue Feb 20, 2017
@tobie
Revamp interface bindings (#313)
4a8f57e 
* Extract legacy callback interface objects
  out of interface objects. Closes #78.
* Clarify that legacy callback interfaces are function objects.
* Give them a length property. Closes #279. Closes #83.
* Require new for Named Constructors. Closes #275.
* Rely on ES abstract operations for defining
  named constructors, interface objects, and
  legacy callback interface objects.
* Disallow using [NoInterfaceObject] on
  callback interfaces with constants.
* Don't require an interface prototype object for constants.
  Callback interfaces do not have an interface prototype object.
  Their constants sit on the legacy callback interface object itself.
  Closes #281.

Closes #283.
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@tobie @domenic