ES3.1 questions and issues

Allen Wirfs-Brock Allen.Wirfs-Brock at microsoft.com
Wed Mar 18 12:31:26 PDT 2009


>-----Original Message-----
>From: Mark S. Miller [mailto:erights at google.com]
>Sent: Wednesday, March 18, 2009 10:27 AM
...
>See again the language I propose for sort. While leaving the choice of
>sorting algorithm unspecified, I place bounds on the range of side
>effects it may cause even under uncooperative conditions. If we really
>wish to leave the precise algorithm unspecified for these others, the
>same qualifying language could still be applied.
>

The only thing that I see in the language in your previous message that may not be already covered is "[if any of the [[Get]], [[Put]], or [[Delete]] operations fail,] the only side effects sort would cause would be that brought about by calling these other operations."

Personally, I think this concept is already implicit in the sort algorithm and most other algorithms in the specification. However, I wouldn't mind making it explicit for the other array methods if we could also made it explicit that implementation may use alternative algorithms that apply [Get]], [[Put]], or [[Delete]] in possibly different orderings.

Here is my first cut at a generic version of language that might accomplish that:

The above algorithm is intended to describe the result produced by this function in the absence of any error conditions. It is not intended to imply the use of any specific implementation technique. The above algorithm produces its results by using a specific sequence of calls to internal methods and abstract operations.  Implementation may use other algorithms that use a different sequencing of these calls as long as an identical results is obtained in the absence of errors conditions. If any internal method call invokes a get or set function of an accessor property that has side-effects or if an error occurs the observable side-effects of this function are implementation defined but are restricted to those that would be produced by some sequence of the internal method and abstract operation calls in the above algorithm.

Allen


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