on Mon Apr 04 2016, Joe Groff <[email protected]> wrote: >> On Apr 4, 2016, at 12:51 PM, Dave Abrahams <[email protected]> wrote: >> >> >> on Mon Apr 04 2016, Joe Groff <jgroff-AT-apple.com> wrote: >> > >>>> On Apr 4, 2016, at 11:44 AM, Dave Abrahams <[email protected]> wrote: >>>> >>>> >>>> on Mon Apr 04 2016, Joe Groff <jgroff-AT-apple.com> wrote: >>>> >>> >>>>>> On Apr 4, 2016, at 11:05 AM, Dave Abrahams via swift-evolution >>>>>> <[email protected]> wrote: >>>>>> >>>>>> >>>>>> on Mon Apr 04 2016, Erica Sadun <[email protected]> asked: >>>>>> >>>>> >>>>>>> Can you ping me off-list or in another thread and explain what the >>>>>>> issues are? >>>>>> >>>>>> All of the following make me uncomfortable with our leading-dot thang: >>>>>> >>>>>> * The rules for lookup don't seem obvious to me. I admit this is very >>>>>> personal/subjective. >>>>>> >>>>>> * There is some evidence that people think it means something it doesn't >>>>>> (“enum case”), as mentioned in SE-0036. That suggests it is a >>>>>> confusing feature. That confusion may be fairly harmless so far, but >>>>>> still. >>>>>> >>>>>> * The dot doesn't seem to buy enough to be worth the complexity it adds >>>>>> to the language; why not just let those names be looked up without the >>>>>> dot? You can always disambiguate with full qualification if you have >>>>>> to. >>>>> >>>>> Making every unqualified reference context-dependent would be >>>>> impractical. `foo.bar(bas)` would become an exponential search to find >>>>> a contextual type containing a `foo` which has a `bar` member that can >>>>> accept an type containing a `bas` member. >>>> >>>> I don't think I'm talking about making every unqualified reference >>>> context-dependent. When I have a context that demands an instance of a >>>> particular enum type, I think it's reasonable to look up the names in >>>> the enum without qualification, and I strongly question the value of >>>> leading-dot syntax for general static member lookup. >>> >>> Therein lies the rub—*any* context an unqualified name can appear in >>> could potentially demand an instance of a particular enum type, until >>> the type checker rules that out. Limiting the behavior to enums >>> doesn't simplify the implementation. >> >> I'm afraid I don't understand how that's a serious problem yet. > > Right now, we limit the contextual lookup to places where it's > syntactically asked for, using the leading dot. Without the leading > dot, we'd have to extend it to every unqualified name, which makes it > much more likely you'll fall into problematic cases.
I don't know how to evaluate whether that likelihood is a problem in practice, or not, though. -- Dave _______________________________________________ swift-evolution mailing list [email protected] https://lists.swift.org/mailman/listinfo/swift-evolution
