Clarification needed on 10.2.1.1.3 SetMutableBinding on a Declarative Environment Record

Allen Wirfs-Brock Allen.Wirfs-Brock at microsoft.com
Tue Jun 22 09:12:28 PDT 2010


Agreed.  I will correct it in the errata

From: es5-discuss-bounces at mozilla.org [mailto:es5-discuss-bounces at mozilla.org] On Behalf Of Mark S. Miller
Sent: Saturday, June 05, 2010 11:03 PM
To: Brendan Eich
Cc: es-discuss; es5-discuss at mozilla.org
Subject: Re: Clarification needed on 10.2.1.1.3 SetMutableBinding on a Declarative Environment Record


On Sat, Jun 5, 2010 at 11:02 PM, Mark S. Miller <erights at google.com<mailto:erights at google.com>> wrote:
The text for SetMutableBinding in table 17 is correct:

[...] If S is true and
the binding cannot be set throw a TypeError exception. S is
used to identify strict mode references.

supporting the notion that the text in 10.2.1.1.3 is an errata.

Or rather, is a mistake to be fixed in an errata ;).


On Sat, Jun 5, 2010 at 10:27 PM, Mark S. Miller <erights at google.com<mailto:erights at google.com>> wrote:
On Sat, Jun 5, 2010 at 10:01 PM, Brendan Eich <brendan at mozilla.com<mailto:brendan at mozilla.com>> wrote:
On Jun 5, 2010, at 9:41 PM, Mark S. Miller wrote:



Am I misunderstanding something, or 2) was this the intended spec, or 3) are these three browsers all non-conformant in the same manner? If the 3rd, I'll file bugs on this. If the 2nd, should we add a correction to the ES5 errata?




Whatever happened to "don't break the web"? :-P

The ES3 spec has no exception here. If ES5 introduced an incompatible change, we should issue an erratum.

+1. I suggest replacing the text I quote above with

If the binding is an immutable binding and S is true, then a TypeError is thrown.

And algorithmic step 4:

4. Else this must be an attempt to change the value of an immutable binding so throw a TypeError exception.

should be changed to

4. Else this must be an attempt to change the value of an immutable binding, so
a. If S is true, throw a TypeError exception.


/be



--
    Cheers,
    --MarkM


--
    Cheers,
    --MarkM



--
    Cheers,
    --MarkM
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