Yes, this is the reason why I didn't mention the variable declaration in initial proposal - it is 100% valid syntax in current implementation (and 100% relative error in strict mode)
But the design problems of ASI are incomparable with a special case of get and set 2017-09-13 17:55 GMT+03:00 Jeremy Martin <[email protected]>: > Quick side note regarding multiple variable declarations: both versions of > this proposal (OP's newline-based proposal and the ASI-inspired version) > result in code breakage: > > ``` > const > x = 5 > y = 6 > z = 7 > ``` > > Under existing ASI rules, this is currently equivalent to: > > ``` > const x = 5; > // y and z are global > y = 6; > z = 7; > ``` > > If we use newline based comma insertion (or give ASI-style comma insertion > precedence over semicolon insertion), then this proposal would result in > the following equivalent: > > ``` > const > x = 5, > // y and z are now lexically scoped constants > y = 6, > z = 7; > ``` > > Unless I'm missing something, both of those scenarios definitely preclude > multiple variable declarations from this proposal. > > That being said, the ASI-inspired semantics seems like it could have more > legs in other contexts, although I would personally argue that too little > is offered in exchange for the cognitive overhead of a new rule with > ASI-style exceptions attached to it (i.e.., "comma before newlines, except > after get, and set, variable declarations, ..."). > > > On Wed, Sep 13, 2017 at 9:57 AM, Naveen Chawla <[email protected]> > wrote: > >> I'm not really familiar with ASI but they key factor mentioned in this >> discussion is this (by Claude Pache): >> >> *A implicit semicolon is not added when a declaration would be complete, >> but when the next token would produce a syntax error. * >> >> By this behaviour (a modification to the initial "complete statement >> produces comma" version of this proposal), everything would work perfectly, >> no? >> >> The multi-line get would not produce a comma, and hence the scheme is >> backwards compatible, right? >> >> Please provide a counter-example if I have missed something. >> >> As for the benefit, the time savings in not having to debug accidentally >> omitted commas and not having to add them in the first place are, I think, >> an improvement. And of course those who want to continue using commas >> everywhere, can: >> >> ```js >> function doStuff( >> x >> y >> z >> ){ >> } >> ``` >> >> ``` >> const >> x = 5 >> y = 6 >> z = 7 >> ``` >> >> Great to hear those counter-examples as I don't know enough about ASI, >> and the related subject, to picture the pitfalls (sorry for my ignorance on >> this). Also it would be good for reference on this proposal... >> >> On Wed, 13 Sep 2017 at 18:40 Boris Zbarsky <[email protected]> wrote: >> >>> On 9/13/17 9:05 AM, Naveen Chawla wrote: >>> > Can someone remind me of the problem doing it this way, if any? >>> >>> You mean apart from all the existing footguns ASI has? >>> >>> -Boris >>> _______________________________________________ >>> es-discuss mailing list >>> [email protected] >>> https://mail.mozilla.org/listinfo/es-discuss >>> >> >> _______________________________________________ >> es-discuss mailing list >> [email protected] >> https://mail.mozilla.org/listinfo/es-discuss >> >> > > > -- > Jeremy Martin > 661.312.3853 <(661)%20312-3853> > @jmar777 <https://twitter.com/jmar777> / @j <https://stream.live/j> > > > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss > >
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