<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">COpaquePointer is IMO a vestige that should be eliminated completely. We'd ultimately like to import opaque C structs as distinct, non-constructible types in Swift, so that they can still be well-typed UnsafePointer<OpaqueThing> types in Swift.<div class=""><br class=""></div><div class="">-Joe</div><div class=""><br class=""><div><blockquote type="cite" class=""><div class="">On Dec 8, 2015, at 12:26 AM, Jacob Bandes-Storch 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 dir="ltr" class="">One hopes to avoid COpaquePointer and Unsafe(Mutable)Pointer, but in practice I've had occasion to use them a few times.<div class=""><br class=""></div><div class="">Things that are nice:</div><div class=""><br class=""></div><div class="">- Unmanaged.passUnretained/takeRetained/etc. which make memory management semantics explicit.</div><div class=""><div class=""><br class=""></div><div class="">Things I've been frustrated by:</div><div class=""><br class=""></div><div class="">- An API takes UnsafeMutablePointer<Void>, but Unmanaged.toOpaque() returns a COpaquePointer.</div><div class=""><br class=""></div><div class="">- An API gives me UnsafeMutablePointer<Void>, but Unmanaged.fromOpaque() takes a COpaquePointer.</div><div class=""><br class=""></div><div class=""><br class=""></div><div class="">In practice, I end up with monstrosities like:</div><div class=""><br class=""></div><div class=""><span style="font-family:monospace,monospace" class="">Unmanaged.passRetained(CFCopyDescription(Unmanaged<AnyObject>.fromOpaque(COpaquePointer($0)).takeUnretainedValue()))</span></div><div class=""><br clear="all" class=""><div class=""><div class="gmail_signature"><div dir="ltr" class=""><div class=""><br class=""></div><div class="">I think a few things could help:</div><div class=""><br class=""></div><div class="">- Phase out COpaquePointer in favor of UnsafePointer<Void> (is this already happening?)</div><div class=""><br class=""></div><div class="">- Add implicit conversion from COpaquePointer to Unsafe(Mutable)Pointer<Void>, and/or vice versa.</div><div class=""><br class=""></div><div class="">- Even better, add implicit conversion from Unmanaged<T> to COpaquePointer or UnsafePointer<Void>, behaving the way toOpaque() currently does. Also, replace Unmanaged.fromOpaque() with an initializer Unmanaged(_: UnsafePointer<Void>).</div><div class=""><br class=""></div><div class=""><br class=""></div><div class="">What are others' experiences? Would it be feasible/favorable to have some of these conversions?</div><div class=""><br class=""></div><div class="">Jacob Bandes-Storch<br class=""></div></div></div></div>
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