<div dir="ltr">On Mon, Jul 18, 2016 at 10:57 AM, Erica Sadun via swift-evolution <span dir="ltr"><<a href="mailto:swift-evolution@swift.org" target="_blank">swift-evolution@swift.org</a>></span> wrote:<br><div class="gmail_extra"><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word"><br><div><blockquote type="cite"><span class=""><div>On Jul 13, 2016, at 5:39 PM, Dave Abrahams via swift-evolution <<a href="mailto:swift-evolution@swift.org" target="_blank">swift-evolution@swift.org</a>> wrote:</div><br></span><div><span class=""><br style="font-family:Palatino-Roman;font-size:14px;font-style:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"><span style="font-family:Palatino-Roman;font-size:14px;font-style:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;float:none;display:inline!important">on Wed Jul 13 2016, Brent Royal-Gordon <</span><a href="mailto:swift-evolution@swift.org" style="font-family:Palatino-Roman;font-size:14px;font-style:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px" target="_blank">swift-evolution@swift.org</a><span style="font-family:Palatino-Roman;font-size:14px;font-style:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;float:none;display:inline!important">> wrote:</span><br style="font-family:Palatino-Roman;font-size:14px;font-style:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"></span><span class=""><blockquote type="cite" style="font-family:Palatino-Roman;font-size:14px;font-style:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"><span style="font-weight:normal">I think grouping these into a type is a sensible approach, but I don't<br>like that</span><b> it allows the creation of meaningless MemoryLayout<br>instances</b>. The simplest fix would be to make `MemoryLayout` an empty<br>enum instead of an empty struct. This would convey that no<br>MemoryLayout instances do or can exist.<br></blockquote><br style="font-family:Palatino-Roman;font-size:14px;font-style:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"><span style="font-family:Palatino-Roman;font-size:14px;font-style:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;float:none;display:inline!important">+1.</span><br style="font-family:Palatino-Roman;font-size:14px;font-style:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"></span></div></blockquote></div><br><div>+1 as well.</div></div></blockquote><div><br></div><div>I must be missing something. How would one create MemoryLayout instances without a public initializer? Why would it matter if stdlib could formally do so internally, given the plethora of much less harmless things that stdlib can do internally?</div><div><br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word"><div><span style="color:rgb(5,0,0);font-family:monospace,serif;font-size:17px;white-space:pre-wrap;background-color:rgb(255,254,254)">/// Accesses the memory layout of `T` through its</span><br></div><div><pre style="font-family:monospace,serif;font-size:17px;white-space:pre-wrap;word-wrap:break-word;color:rgb(5,0,0);background-color:rgb(255,254,254)">/// `size`, `stride`, and `alignment` properties
public enum MemoryLayout {
/// Returns the contiguous memory footprint of `T`.
///
/// Does not include any dynamically-allocated or "remote"
/// storage. In particular, `MemoryLayout.size`, when
/// `T` is a class type, is the same regardless of how many
/// stored properties `T` has.
public static var size: Int { return _sizeof(T.self) }
/// For instances of `T` in an `Array`, returns the number of
/// bytes from the start of one instance to the start of the
/// next. This is the same as the number of bytes moved when an
/// `UnsafePointer` is incremented. `T` may have a lower minimal
/// alignment that trades runtime performance for space
/// efficiency. The result is always positive.
public static var stride: Int { return _strideof(T.self) }
/// Returns the default memory alignment of `T`.
public static var alignment: Int { return _alignof(T.self) }
}</pre><span class="HOEnZb"><font color="#888888"><div><br></div></font></span></div><span class="HOEnZb"><font color="#888888"><div><br></div><div>-- E</div><div><br></div></font></span></div><br>_______________________________________________<br>
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