On Friday, April 7, 2017, Daniel Duan via swift-evolution < [email protected]> wrote:
> Hi all, > > In a discussion about inferring parameter types from default value, Slava > brought up some performance problems caused by type inference for stored > properties in side types: > > https://lists.swift.org/pipermail/swift-evolution/ > Week-of-Mon-20170313/033882.html > > Towards the end, the post mentioned that some Swift team members > contemplated requiring types for stored properties in type declarations. I > think this idea deserves some more attention. Hence this last minute > idea-floating. > > In addition to solving a performance headache in implementation, there're > always the general benefit of making type declartion more explicit and > readable (clarity for reader should out-weigh pleasure of the author). > Making the > language slightly more consistent (we are not inferring types for default > parameter values in function anyways). > > The cons for doing this are obvious too: the inference makes the language > feels more friendly and is, undoubtedly, a beloved feature for many. This > would be a source breaking change. > > Just thought I'd float the idea to gather some quick reaction. What do > y'all think? > I think this chabge would be too source breaking for Swift 4. Just for that reason I would not implement it. Also, I think the Core team talked about having specific themes for the upcoming releases. I would very much like Swift 5 to have improving compile times as a major theme. Under such theme, maybe it makes sense to forbid complex expressions in stored properties definitions with no explicit type. Forbidding literals or direct function calls would remove a useful feature and the gains would not be much, IMHO. -- Víctor Pimentel -- INNOVATION IN PERSONAL COMMS *[image: Imágenes integradas 5]* *Víctor Pimentel Rodríguez · *Principal iOS Engineer [email protected] +34 914 294 039 <+34914294039> — +34 687 840 886 <+34687840886> C/ Gran Vía, nº 28, 6ª planta — 28013 Madrid Tuenti Technologies, S.L. www.tu.com www.tuenti.com
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