980828 - Generator and array comprehensions should support destructuring binding

Status: RESOLVED WONTFIX

(Core :: JavaScript Engine, defect)

Description

[Andy Wingo [:wingo]]

The first version of ES6 array and generator comprehensions (bug 979865) does not do destructuring binding.  It should.

Comment 1

[:Paolo Amadini]

This may be handy in cases like this (from bug 1164028):

  events: {
    mainview: {
      focus(event) {},
    },
    filter: {
      input(event) {},
    },
  },

So, instead of:

  this.boundEventHandlers = [
    for (elementName of Object.keys(this.events))
    for (eventName of Object.keys(this.events[elementName]))
    [elementName, eventName, this.events[elementName][eventName].bind(this)]
  ];

I could use:

  this.boundEventHandlers = [
    for ([elementName, events] of Iterator(this.events))
    for ([eventName, handler] of Iterator(events))
    [elementName, eventName, handler.bind(this)]
  ];

However, I'm not sure what is the standard alternative to Iterator in this case...

Comment 2

[Jason Orendorff [:jorendorff]]

Not an ES6 feature anymore; detaching from that dependency tree.

Comment 3

[David Bruant]

This is not standard and i have not seen a corresponding proposal in https://github.com/tc39/proposals
This bug should probably be closed and a new one re-opened when a proposal emerges and reaches stage 2 or 3 (or there is interest from the SpiderMonkey team to experiment before that)

Comment 4

[David Bruant]

Also, Generator and array comprehensions were removed somewhere in bug 1220564 and bug 1414340

Comment 5

[André Bargull [:anba]]

See comment #4.