<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=""><div><blockquote type="cite" class=""><div class=""><div class="gmail_extra" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><div class="gmail_quote"><blockquote class="gmail_quote" style="margin: 0px 0px 0px 0.8ex; border-left-width: 1px; border-left-style: solid; border-left-color: rgb(204, 204, 204); padding-left: 1ex;"><div style="word-wrap: break-word;" class=""><span class=""><div class=""><blockquote type="cite" class=""><div class=""><div class="gmail_quote" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;"><div class=""><br class=""></div><div class="">The problem is I would expect to be able to safely call deinitialize() and friends after calling initialize(from:). If Element is a class type and initialize doesn’t fill the entire buffer range, calling deinitialize() will crash. That being said, since copy(from:bytes:) and copyBytes(from:) don’t do any initialization and have no direct counterparts in UnsafeMutableBufferPointer, it’s okay if they have different behavior than the other methods.</div></div></div></blockquote><br class=""></div></span><div class=""><div class="">You astutely pointed out that the UnsafeMutableBufferPointer.<wbr class="">deinitialize() method is dangerous, and I asked you to add a warning to its comments. However, given the danger, I think we need to justify adding the method to begin with. Are there real use cases that greatly benefit from it?</div></div></div></blockquote></div></div><div class="gmail_extra" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><br class=""></div><div class="gmail_extra" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;">I agree that’s a problem, which is why i was iffy on supporting partial initialization to begin with. The use case is for things like growing collections where you have to periodically move to larger storage. However, deinitialize is no more dangerous than moveInitialize, assign(repeating:count:), or moveAssign; they all deinitialize at least one entire buffer. If deinitialize is to be omitted, so must a majority of the unsafe pointer API.</div></div></blockquote></div><br class=""><div class=""><div class="">Here's an alternative. Impose the precondition(source.count == self.count) to the following UnsafeMutableBufferPointer convenience methods that you propose adding:</div><div class=""><br class=""></div><div class="">+++ func assign(from:UnsafeBufferPointer<Element>)</div><div class="">+++ func assign(from:UnsafeMutableBufferPointer<Element>)</div><div class="">+++ func moveAssign(from:UnsafeMutableBufferPointer<Element>)</div><div class="">+++ func moveInitialize(from:UnsafeMutableBufferPointer<Element>)</div><div class="">+++ func initialize(from:UnsafeBufferPointer<Element>)</div><div class="">+++ func initialize(from:UnsafeMutableBufferPointer<Element>)</div><div class=""><br class=""></div><div class="">I don't that introduces any behavior that is inconsistent with other methods. `copyBytes` is a totally different thing that only works on trivial types. The currently dominant use case for UnsafeBufferPointer, partially initialized backing store, does not need to use your new convenience methods. It can continue dropping down to pointer+count style initialization/deinitialization.</div></div><div class=""><br class=""></div><div class="">-Andy</div></body></html>