On Fri, Jul 19, 2013 at 3:21 PM, Tab Atkins Jr. <jackalmage at gmail.com>wrote:

> On Fri, Jul 19, 2013 at 1:21 PM, Rick Waldron <waldron.rick at gmail.com>
> wrote:
> > On Fri, Jul 19, 2013 at 1:35 PM, Tab Atkins Jr. <jackalmage at gmail.com>
> > wrote:
> >>
> >> On Thu, Jul 18, 2013 at 4:34 PM, Andy Earnshaw <andyearnshaw at gmail.com>
> >> wrote:
> >> > It's potentially a breaking change, because
> >> >
> >> > 0 < 1 < 1
> >> >
> >> > evaluates to false in current implementations because
> >> >
> >> > (0 < 1) < 1
> >>
> >> Luckily, this is false in the chained operations too, since "(0 < 1)
> >> && (1 < 1)" evaluates to false.
> >>
> >> One problem is that in current Javascript, the equality and the
> >> comparison operators are at different precedence levels.  Python puts
> >> them at the same level, so that chaining can be purely left-to-right.
> >> There's a decent chance that code does indeed depend on this, due to
> >> testing equality of a comparison with a bool (which is stupid, but
> >> people do it).
> >
> > While this is all true, the simple answer is:
> >
> > var a = 1, b = 2, c = 3;
> > a < b < c; // true
> >
> > is already valid JavaScript and can't be co-opted to express new runtime
> > evaluation semantics.
>
> Well, that's a bad example, because it's true with chained operators
> too.  Let c = 1.5, though, and you get different behavior.
>
> This type of code is broken in the first place, though.  Are we
> assuming that it's prevalent enough to cause problems?
>

It doesn't matter if you think my example is a "bad example", it's a valid
expression per the language's existing grammar.

Rick
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It doesn't matter if you think my example is a "bad example", it's a valid expression per the language's existing grammar.