Enumerability

Allen Wirfs-Brock allen at wirfs-brock.com
Sat Jan 11 09:33:54 PST 2014


On Jan 11, 2014, at 9:01 AM, Axel Rauschmayer wrote:

>>> ### I’m looking for a simple explanation of what enumerability will be, going forward. If there isn’t one then I’d argue that no new feature should be influenced by it.
>> 
>> That was one of the argument made in favor of concise methods defaulting as not enumerable: enumerable really only controls whether a property shows up in for-in (and a couple closely related reflection functions) and for-in has been essentially deprecated and replace by for-of.  That makes the enumerable attribute an obsolete feature and we should be trying to give it meaning for new features.  Hence, just always default it to true.
> 
> Good point. That “meaning for new features” should probably be clearly stated and dictate how `Object.assign()` behaves.
> 
> I know this runs counter the conventional wisdom for specs, but I find design rationales incredibly important for making sense of what’s going on: The answers and discussions on this mailing list were essential in helping me understand the language.

I happily put in informative NOTE's when it seems important to clarify intent for  implementors (and even future spec. editors).  Feel free to file bugs any time you find a place in the spec. where you think something needs to be clarified in that manner. 

You guys who read the drafts are the beta testers of the specification and your feedback is really useful for finding places where the clarity needs to be improved.

Allen



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