Attribute defaults for Object.defineProperty

Neil Mix nmix at
Thu Aug 21 08:34:49 PDT 2008

At the risk of beating a dead horse too much, based on the info you  
provided it sounds like the "flexible" attribute isn't really an  
attribute of the property, but an attribute of the attributes.  Sort  
that out appropriately in the APIs and the terminology may flow more  

On Aug 21, 2008, at 9:55 AM, Allen Wirfs-Brock wrote:

> Or arguably "reconfigurable".
> We've had several discussions of most of these alternatives and so  
> the consensus has been to stick with "flexible". We'll talk about it  
> again today, but I wouldn't be surprised if the outcome is the same.
> Allen
>> -----Original Message-----
>> From: Neil Mix [mailto:nmix at]
>> Sent: Thursday, August 21, 2008 7:38 AM
>> To: Allen Wirfs-Brock
>> Cc: Brendan Eich; Mark S. Miller; es-discuss at
>> Subject: Re: Attribute defaults for Object.defineProperty
>> writable: can be written to
>> enumerable: can be enumerated
>> flexible: can be flexed?
>> how about configurable?
>> On Aug 20, 2008, at 5:31 PM, Allen Wirfs-Brock wrote:
>>>> From: Brendan Eich [mailto:brendan at]
>>>> Sent: Wednesday, August 20, 2008 11:25 AM
>>> [snip]
>>>> Hi Allen, could you remind me and a few others who were wondering
>>>> yesterday (sorry I don't remember -- it's in minutes, somewhere)  
>>>> why
>>>> [[Deletable]] was not chosen instead of [[Flexible]]? Thanks.
>>> The reason for not using "deletable" was originally explained in the
>>> message below.  I believe that at one of the phone meetings after
>>> Oslo we briefly discussed changing it back to "dynamic" or possibly
>>> something else but the consensus was to stick with "flexible".
>>>> -----Original Message-----
>>>> From: es3.x-discuss-bounces at [mailto:es3.x-discuss-
>>>> bounces at] On Behalf Of Allen Wirfs-Brock
>>>> Sent: Thursday, June 26, 2008 1:39 PM
>>>> To: es3.x-discuss at x-discuss; es4-discuss at
>> es4-
>>>> discuss
>>>> Subject: RE: "dynamic" attribute nomenclature
>>>> At today's ES 3.1 conference call (see
>>>> id=meetings:minutes_jun_24_2008)
>>>> we agreed to use the term "Flexible" for the property attribute  
>>>> that
>>>> we recently had been calling "Dynamic" and which subsumes the
>>>> DontDelete attribute.
>>>> From: Allen Wirfs-Brock
>>>> Sent: Wednesday, June 25, 2008 10:37 AM
>>>> To: Lars Hansen; Mark S. Miller
>>>> Cc: es3.x-discuss at x-discuss
>>>> Subject: "dynamic" attribute nomenclature
>>>> In Lars's feedback on the the June 11, ES3.1 draft he said:
>>>> p26 8.6.1.  (And throughout the spec) The meaning of "dynamic" in
>> ES4
>>>> is something else (it means a non-fixture property).  It would
>>>> probably
>>>> reduce confusion if the property name Deletable were used here,  
>>>> as I
>>>> though we had agreed previously.
>>>> Dynamic as currently used in ES3.1 means more than just Deletable,
>> it
>>>> also means that the property attributes (including the Dynamic
>>>> attribute) can be modified and that it can be transformed  between
>>>> being a data and procedural property. Hence, the name Deletable
>> seems
>>>> to imply something too narrow.
>>>> Playing around with the thesaurus, the best "positive, active term
>>>> that
>>>> I could find that seems to be a reasonable description of this
>>>> semantics is:
>>>>     Alterable
>>>> (other, perhaps less satisfy or otherwise unacceptable alternatives
>>>> include: changeable, mutable, modifiable, flexible, amendable)
>>>> Note this would mean  that data properties would expose properties
>>>> named Writable and Alterable.  My sense is that there is enough
>>>> conceptual  distance between those terms that there won't be too
>> much
>>>> confusion.
>>>> Thoughts??
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