[swift-evolution] C-style For Loops

[Kevin Ballard]

A straight translation using UnsafePointer without a C-style for loop
would look like

func blk_xor(dst: UnsafeMutablePointer<CChar>, src:
UnsafePointer<CChar>, len: Int) -> UnsafeMutablePointer<CChar> {
    for i in 0..<len {
        dst[i] ^= src[i]
    }
    return dst
}

-Kevin Ballard

On Thu, Dec 3, 2015, at 09:47 PM, ChanMaxthon wrote:
> How about this C code when rewritten in Swift:
> 
> char *blk_xor(char *dst, const char *src, size_t len)
> {
>   const char *sp = src;
>   for (char *dp = dst; sp - src < len; sp++, dp++)
>     *dp ^= *sp;
>   return dst;
> }
> 
> Sent from my iPhone
> 
> > On Dec 4, 2015, at 13:35, Sean Heber <sean at fifthace.com> wrote:
> > 
> > I found a couple of cases of them in my codebase, but they were trivially transformed into “proper” Swift-style for loops that look better anyway. If it were a vote, I’d vote for eliminating C-style.
> > 
> > l8r
> > Sean
> > 
> > 
> >> On Dec 3, 2015, at 6:52 PM, Kevin Ballard <kevin at sb.org> wrote:
> >> 
> >> Every time I've tried to use a C-style for loop, I've ended up switching to a while loop because my iteration variable ended up having the wrong type (e.g. having an optional type when the value must be non-optional for the body to execute). The Postmates codebase contains no instances of C-style for loops in Swift.
> >> 
> >> -Kevin Ballard
> >> 
> >>> On Thu, Dec 3, 2015, at 04:50 PM, Eric Chamberlain wrote:
> >>> We’ve developed a number of Swift apps for various clients over the past year and have not needed C style for loops either.
> >>> 
> >>> 
> >>> --
> >>> Eric Chamberlain, Lead Architect - iOS
> >>> ArcTouch - App Development Studio
> >>> 
> >>> Custom apps for world-class brands and the Fortune 500
> >>> arctouch.com/work | arctouch.com/blog
> >>> 
> >>> 
> >>> 
> >>> 
> >>>> On Dec 3, 2015, at 3:46 PM, Andy Matuschak <andy at andymatuschak.org> wrote:
> >>>> 
> >>>> Just checked; ditto Khan Academy.
> >>>> 
> >>>>> On Dec 3, 2015, at 3:43 PM, Keith Smiley <keithbsmiley at gmail.com> wrote:
> >>>>> 
> >>>>> For what it's worth we don't have a single C style for loop in the Lyft
> >>>>> codebase.
> >>>>> 
> >>>>> --
> >>>>> Keith Smiley
> >>>>> 
> >>>>>> On 12/03, Douglas Gregor wrote:
> >>>>>> 
> >>>>>>> On Dec 3, 2015, at 3:32 PM, Erica Sadun <erica at ericasadun.com> wrote:
> >>>>>>> 
> >>>>>>> Does Swift still needs C-style for loops with conditions and incrementers? 
> >>>>>>> 
> >>>>>>> <Screen Shot 2015-12-03 at 4.30.15 PM.png>
> >>>>>>> 
> >>>>>>> More Swift-like construction is already available with for-in-statements and stride. 
> >>>>>>> This would naturally starve the most common point for -- and ++ operators as well.
> >>>>>> 
> >>>>>> My intuition *completely* agrees that Swift no longer needs C-style for loops. We have richer, better-structured looping and functional algorithms. That said, one bit of data I’d like to see is how often C-style for loops are actually used in Swift. It’s something a quick crawl through Swift sources on GitHub could establish. If the feature feels anachronistic and is rarely used, it’s a good candidate for removal.
> >>>>>> 
> >>>>>> - Doug
> >>>>> 
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