[swift-evolution] My personal beef with leading-dot syntax

Dave Abrahams dabrahams at apple.com
Mon Apr 4 13:44:23 CDT 2016

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 <swift-evolution at swift.org> wrote:
>> on Mon Apr 04 2016, Erica Sadun <swift-evolution at swift.org> 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.  I would normally
never think of using it that way—because, guess what? I think of
leading-dot as a notation for enums like everybody else does—and I don't
think there are any important idioms it supports, that couldn't be
equally well handled by something like `Self.x` if we were allowed to
use it.


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