On Nov 21, 2010, at 7:40 PM, Mark S. Miller wrote: > On Sun, Nov 21, 2010 at 7:05 PM, Brendan Eich <[email protected]> wrote: > On Nov 18, 2010, at 4:08 PM, Waldemar Horwat wrote: > [...] > Worse, the use of colon in this new for syntax is confusingly similar to > long-standing future-proofing intentions around runtime type annotations (aka > guards or contracts). > > (BTW, I don't think :: is a good type annotation or guard punctuator, btw -- > it's the C++ namespace qualification operator, also specified for namespacing > by ECMA-357 (E4X) and used that way in ActionScript 3 (and in ES4, RIP). So I > was surprised to see :: used for annotation-like syntax in > http://wiki.ecmascript.org/doku.php?id=strawman:guards and > http://wiki.ecmascript.org/doku.php?id=strawman:trademarks.) > > Note that I do not consider the trademarks strawman ready for discussion. > Accordingly I had recently moved it from the strawman page to the deferred > page. I want to do a rather extensive rewrite before I'll be happy enough > with it.
Thanks, I didn't mean to spotlight it, hence my parentheses (and double BTW/btw ;-). > I think the guards strawman is in fine shape for discussion. It postpones > most of the semantic issues to other specs (like trademarks eventually) that > would parameterize the guards strawman by proposing a concrete meaning for > its internal Coerce___ function. > > The reason I chose "::" over ":" is not for a love of "::". Alternative > suggestions appreciated! However, I avoided ":" so that we could guard > properties within object literals > <http://wiki.ecmascript.org/doku.php?id=strawman:guards#guarding_properties>. > I don't see a way to use ":" for that without confusion. The ES4 solution -- > that one can only annotate an object literal as a whole but not its > individual properties -- always seemed unpleasant. :: is strictly less pleasant, and really kind of "taken" due to the precedents I cited. The "less pleasant" point is the big one IMHO. /be
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