<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><br class=""><div><blockquote type="cite" class=""><div class="">On Dec 1, 2016, at 11:33 PM, Nate Cook via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class="">3) Make all buffer pointers their own slices but use a different index type. If the indices were just wrapped pointers, that would handle the index sharing without needing an additional property on the buffer. We could also maintain integer-based stridable conformance (which greatly simplifies index arithmetic), since the indices would just offset by a byte for raw buffers or a stride for typed buffers.</div><br class="Apple-interchange-newline"></div></blockquote></div><br class=""><div class="">Unfortunately, switching to non-integer indices would change this from being mildly source-breaking to being extremely source-breaking, as there’s lots of code out there using buffers today indexing them with integers (including integer literals).</div><div class=""><br class=""></div><div class="">The big win with UnsafeBufferPointer having an integer index is it’s a drop-in replacement for arrays, so when you hit a performance problem using an array you can quickly switch to using a buffer under most circumstances instead without having to change much of your code – including code that uses <font face="Menlo" class="">for i in 0..<myArray.count</font>, of which there is a lot out there in the wild. Switching to an opaque index would break anyone doing that.</div><div class=""><br class=""></div></body></html>