Array.prototype.sort: order and moment of the [[Get]]/[[Set]] calls

Claude Pache claude.pache at gmail.com
Mon Aug 18 04:32:10 PDT 2014


Le 18 août 2014 à 12:59, Till Schneidereit <till at tillschneidereit.net> a écrit :

> 
> Note also that, by my reading of the spec at least, all implementations currently fully adhere to the spec: they "[p]erform an implementation-dependent sequence of calls to the [[Get]] and [[Set]] internal methods of obj, to the DeletePropertyOrThrow abstract operation with obj as the first argument, and to SortCompare". My reading of this is that "implementation-denendent sequence" refers to all four mentioned functions, where an implementation might either intermix all of them (like v8/JSC do) or first do a (sub-)sequence of only [[Get]] calls and then a second (sub-)sequence intermixing calls to all the other functions (like Chakra/SpiderMonkey).
> 

Nit: As currently specced, SortCompare includes obligatory calls to [[HasProperty]] and [[Get]] on some keys before invoking the comparison function: so, SpiderMonkey/Chakra don't adhere to the specs. Even JSC/V8 don't fully adhere to the spec on this point, because (as I've observed) they may omit a call to [[HasProperty]]/[[Get]] when the value is known. But I think it is a spec bug that can be corrected, in order to make all current implementations compliant (SortCompare should take the values, not the keys, as arguments).

—Claude


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