This is related to what I was trying to figure out in the "more fun with
undefined" thread, maybe it is wrong or have too many impact but I was
about to suggest :
8.9.1 GetValue (V)
...
5. If IsUnresolvableReference(V), return undefined
11.2.1 Property Accessors
Runtime Semantics: Evaluation
...
3. If baseValue is an abrupt completion or undefined, return baseValue.
Why not, instead of adding "?" operator ?
Le 18/06/2012 07:11, Brendan Eich a écrit :
Sorry, meant to start a new thread for:
http://wiki.ecmascript.org/doku.php?id=strawman:existential_operator
As the Syntax section hints, we can't also adopt CoffeeScript's ?(
variant, which enables foo.bar?(args, go, here).baz and the like. The
C syntax heritage prevails.
/be
Brendan Eich wrote:
David Herman wrote:
On Jun 15, 2012, at 5:57 PM, satyr wrote:
On Sat, Jun 16, 2012 at 4:33 AM, David Herman <dher...@mozilla.com
<mailto:dher...@mozilla.com>> wrote:
As for null, I can see how there's confusion about whether to use
null vs undefined, and so I can see why CoffeeScript would just
try to blur the distinction between them.
Not just for blurring. Rejecting `null` is essential for
CoffeeScript's "existence" due to `?.`, the soak/safe access operator.
I think you could make a case for ?. defaulting for both but ??
defaulting only undefined. The case goes something like this:
- The purpose of ?? is to provide a default value when no value was
provided. The way to say "no value" in JavaScript is undefined.
- The purpose of ?. is to fail soft when doing a property lookup.
Both null and undefined throw when doing a property lookup.
Agreed. This is one choice, it's plausible because of the distinction
between defaulting (which requires intentional passing of a "please
default" sentinel value, or not passing a trailing actual argument)
and soaking up null-or-undefined.
Yes, we could make ?? and ??= do the same for null as for undefined.
I'm not sure that's the right choice, but it's a choice. For
foo.bar?.baz, though, the clearer choice is to avoid throwing, which
means evaluating to undefined if foo.bar is missing (evaluates to
undefined) *or* has a value not coercible to object type (null or
undefined). See
http://wiki.ecmascript.org/doku.php?id=strawman:existential_operator
/be
_______________________________________________
es-discuss mailing list
es-discuss@mozilla.org
https://mail.mozilla.org/listinfo/es-discuss
_______________________________________________
es-discuss mailing list
es-discuss@mozilla.org
https://mail.mozilla.org/listinfo/es-discuss
--
jCore
Email : avi...@jcore.fr
Web : www.jcore.fr
Webble : www.webble.it
Extract Widget Mobile : www.extractwidget.com
BlimpMe! : www.blimpme.com
_______________________________________________
es-discuss mailing list
es-discuss@mozilla.org
https://mail.mozilla.org/listinfo/es-discuss
