-----Messaggio originale----- From: Brendan Eich Sent: Wednesday, February 12, 2014 2:00 AM To: Nathan Wall Cc: Giacomo Cau ; es-discuss@mozilla.org Subject: Re: Another switch
Definitely good to see new languages being designed and implemented. JS is not going to break compatibility on the old fall-through behavior of switch, inherited from Java from C++ from C. All the C-like languages copy this flaw, because to do otherwise with the same keyword would be worse (confused users cross-training and -coding among languages would want our scalps), and IMHO using novel reserved words would be hardly better. /be > Nathan Wall <mailto:nathan.w...@live.com> > February 11, 2014 at 3:21 PM > Hi Giacomo, > > Not sure whether this will be of interest to you, but I have been > working on a JS-derived language called Proto (still highly > experimental) which has a switch statement that works exactly as you > described: > > https://github.com/Nathan-Wall/proto/blob/master/docs/control/switch.md > > Perhaps you will at least find it interesting. :) > > Nathan > yes, so great it would be a pleasure to contribute :) the proposal doesn't want, by no means, to break the compability with the present syntax and/or semantics of the switch. At most, should be considered as an extension of current syntax with a consequential new semantics. the swith, as it is known, should anyhow be written as switch (...) { case ...: ...; break; case ...: ...; break; case ...: ...; case ...: ...; break; otherwise: ... } but, it could be handy to write the same thing with a slightly different syntax: switch (...) break { case ...: ...; case ...: ...; case ...: ...; continue; case ...: ...; otherwise: ... } Some break less, no new keyword, no incompatibility with past. Who shall use it, will know from the start that here, the continue will not lead him at the beginning of the first for or while that englobe the switch, but only at the following case. Then, willingly, we could also think that normal switch be desugared in switch (...) continue { case ...: ...; break; case ...: ...; break; case ...: ...; case ...: ...; break; otherwise: ... } with break and continue (except that between ')' and '{' ) that, obviously, continue as before. This isn't a must, it's just for my pleasure in finding regularity. At last, if we were to look for the burden of a new keyword, even better select (...) { case ...: ...; case ...: ...; case ...: ...; continue; case ...: ...; otherwise: ... } but I realize this could be a break point of the existing code and, onestly speaking, it is beyond my ability to evaluate. Anyhow, thanks for your attention. bye Giacomo Cau
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