On Thu, Jan 19, 2017 at 10:52 AM, Mark S. Miller <[email protected]> wrote:
> > > On Thu, Jan 19, 2017 at 9:30 AM, Boris Zbarsky <[email protected]> wrote: > >> On 1/19/17 12:24 PM, Isiah Meadows wrote: >> >>> 1. What does Firefox do with the getter on non-errors? >>> >> >> Oh, I didn't make that clear, did I? On a non-error in the getter, we >> have an Error object or Error.prototype (which appeared somewhere on our >> receiver's proto chain). Those objects all have, in Spidermonkey, an >> internal slot that stores information about the stack. The getter uses the >> information in that internal slot to create a string and return it. >> >> 2. How breaking is having the getter and setter throwing on non-errors? >>> >> >> Well, when we tried to do it it didn't even pass our test automation, >> so... >> >> In particular it would throw on anyone doing ES5-style subclassing of >> Error and then doing anything with .stack. > > > That makes perfect sense. > > We could have the Error.prototype.getter > I meant: the Error.prototype.stack getter > not throw but have System.getStack throw. There was no strong reason for > the getter and System.getStack to have precisely the same behavior; it was > just that there was no reason not to. Now there is. Thanks. > > > > >> >> >> I'm struggling to see how it'd be that breaking. It's a getter, not a >>> method, so it requires a call to `__locateGetter__` or >>> `Object.defineProperty` to even access. >>> >> >> No, it just requires that you have an Error on your prototype chain but >> not be an Error yourself, and suddenly you have exceptions everywhere. >> >> >> -Boris >> _______________________________________________ >> es-discuss mailing list >> [email protected] >> https://mail.mozilla.org/listinfo/es-discuss >> > > > > -- > Cheers, > --MarkM > > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss > > -- Cheers, --MarkM
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