<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 Apr 15, 2016, at 10:36, Dmitri Gribenko via swift-users <<a href="mailto:swift-users@swift.org" class="">swift-users@swift.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: 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; float: none; display: inline !important;" class="">On Fri, Apr 15, 2016 at 10:34 AM, Chris Lattner <</span><a href="mailto:clattner@apple.com" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: 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="">clattner@apple.com</a><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: 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; float: none; display: inline !important;" class="">> wrote:</span><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: 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=""><blockquote type="cite" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: 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=""><br class=""><blockquote type="cite" class="">On Apr 14, 2016, at 11:22 PM, Dmitri Gribenko <<a href="mailto:gribozavr@gmail.com" class="">gribozavr@gmail.com</a>> wrote:<br class=""><br class="">On Thu, Apr 14, 2016 at 11:16 PM, Chris Lattner via swift-users<br class=""><<a href="mailto:swift-users@swift.org" class="">swift-users@swift.org</a>> wrote:<br class=""><blockquote type="cite" class=""><br class=""><blockquote type="cite" class="">On Apr 14, 2016, at 10:45 AM, soyer via swift-users <<a href="mailto:swift-users@swift.org" class="">swift-users@swift.org</a>> wrote:<br class=""><br class="">Hello Guys, Girls,<br class=""><br class="">Do you know why is the init?(length length: Int) NSMutableData's initializer failable?<br class="">The memory allocation can fail, but I think Swift doesn't handle that cases. (it is not a real issue in a modern OS)<br class="">The code on github calls a non failable initializer.<br class=""><a href="https://github.com/apple/swift-corelibs-foundation/blob/master/Foundation/NSData.swift#L904" class="">https://github.com/apple/swift-corelibs-foundation/blob/master/Foundation/NSData.swift#L904</a><br class=""></blockquote><br class="">Swift’s policy on memory allocation failure is that fixed-size object allocation is considered to be a runtime failure if it cannot be handled. OTOH, APIs that can take a variable and arbitrarily large amount to allocate should be failable. NSData falls into the later category.<br class=""></blockquote><br class="">Does this principle apply to Array(repeating:count:)?<br class="">Array.append(contentsOf:)?<br class=""></blockquote><br class="">As you know well enough, “no”. :-)<br class=""></blockquote><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: 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=""><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: 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; float: none; display: inline !important;" class="">Why? These APIs also "take a variable and arbitrarily large amount to</span><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: 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=""><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: 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; float: none; display: inline !important;" class="">allocate".</span><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: 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=""></div></blockquote></div><br class=""><div class="">I might split the difference here: trying to append a very large sequence would be a programmer error, but trying to allocate a very large array might not be.</div><div class=""><br class=""></div><div class="">UnsafeMutablePointer.init(allocatingCapacity:) is also currently non-failable.</div><div class=""><br class=""></div><div class="">Jordan</div></body></html>