<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 Feb 2, 2017, at 4:02 PM, Rex Fenley <<a href="mailto:rex@remind101.com" class="">rex@remind101.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" class="">But then any time as user of the pipeline I'm writing would like a new type of collection they will be forced to inherit this new protocol vs one they're already familiar with and which the collection may already conform too.</div></div></blockquote><div><br class=""></div><div>Yes, that is true. But if you design your new protocol such that it’s requirements all match a requirement in `RangeReplaceableCollection` then conformance will be a one-line extension. This may not be ideal, but it’s really not too bad and you can do it today.</div><br class=""><blockquote type="cite" class=""><div class=""><div class="gmail_extra"><br class=""><div class="gmail_quote">On Thu, Feb 2, 2017 at 1:53 PM, Matthew Johnson <span dir="ltr" class=""><<a href="mailto:matthew@anandabits.com" target="_blank" class="">matthew@anandabits.com</a>></span> wrote:<br class=""><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word" class=""><br class=""><div class=""><span class=""><blockquote type="cite" class=""><div class="">On Feb 2, 2017, at 3:46 PM, Rex Fenley <<a href="mailto:rex@remind101.com" target="_blank" class="">rex@remind101.com</a>> wrote:</div><br class="m_-7576891152844605977Apple-interchange-newline"><div class=""><div dir="ltr" class="">My use case is RLMArray and it can't implement <span style="font-size:12.8px" class="">RangeReplaceableColl<wbr class="">ection</span> though because `init` is unavailable, additionally, there's a lot of parts to the protocol that would take some time to implement correctly if I could. They offer a Swift type List that wraps RLMArray and does a bunch of stuff to implement <span style="font-size:12.8px" class="">RangeReplaceableColl<wbr class="">ection,</span> but they discourage using their Swift library in mixed Obj-C/Swift projects and certain model objects simply couldn't use the List type anyway because they're also used in Obj-C and List is not @objc compliant.<br class=""><br class="">So this leaves me in situations where when I need to use Array or RLMArray I have to duplicate my code, not just in one place, but all the way down a pipeline in order to have my generics work with either <span style="font-size:12.8px" class="">RangeReplaceableCollect<wbr class="">ion or </span>RLMArray.<br class=""><br class="">If I could abstract the commonalities required by my application, I could just have a RLMArrayProtocol that has RLMArray's exposed function signatures and a new protocol Appendable = <span style="font-size:12.8px" class="">RangeReplaceableCollection | </span>RLMArrayProtocol and this will type check all the way through the pipeline.<div class=""><br class=""></div><div class="">tl;dr - if a function signature required by a protocol is marked unavailable on a class, then disjunction is necessary in order to bridge the two (or more) types without duplicating code.</div></div></div></blockquote><div class=""><br class=""></div></span><div class="">You should be able to solve this problem today by creating a custom protocol that you use as a constraint in your generic code and providing conformances for both Array and RLMArray.</div><div class=""><div class="h5"><br class=""><blockquote type="cite" class=""><div class=""><div class="gmail_extra"><br class=""><div class="gmail_quote">On Thu, Feb 2, 2017 at 1:35 PM, Matthew Johnson <span dir="ltr" class=""><<a href="mailto:matthew@anandabits.com" target="_blank" class="">matthew@anandabits.com</a>></span> wrote:<br class=""><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word" class=""><div class=""><span class=""><blockquote type="cite" class=""><div class=""><br class="">On Feb 2, 2017, at 3:26 PM, Rex Fenley via swift-evolution <<a href="mailto:swift-evolution@swift.org" target="_blank" class="">swift-evolution@swift.org</a>> wrote:</div><br class="m_-7576891152844605977m_4684597058227267120Apple-interchange-newline"><div class=""><div dir="ltr" class="">Hello, I believe there was some discussion about this quite awhile ago. I was wondering if there's any interest in including a protocol 'or' type that would be the intersection of two protocols. This could be really useful in situations where a framework that the user has no control over implements a portion of some often used protocol. Such as specialized collections from an Database framework that don't implement RangeReplaceableCollection but have a set of methods that are equivalent. The user can then implement a protocol that is the intersection of those set of methods and not duplicate code.</div></div></blockquote><div class=""><br class=""></div></span><div class="">If the specialized collection in the database framework already provides functionality equivalent to `RangeReplaceableCollection` what you really want to do is just provide the conformance you’re looking for in an extension:</div><div class=""><br class=""></div><div class="">extension SpecializedDatabaseCollection: RangeReplaceableCollection {</div><div class=""> // if necessary, provide forwarding wrappers where the member names don’t match up.</div><div class="">}</div><div class=""><br class=""></div><div class="">But in a case like this the framework itself really should provide this conformance out of the box. If they didn’t, maybe there is a good reason so you would want to find out why it wasn’t provided.</div><div class=""><br class=""></div><div class="">Is there something you’re hoping to do that you can’t solve by simply extending the framework types?</div><span class=""><br class=""><blockquote type="cite" class=""><div class=""><div dir="ltr" class=""><div class=""><br class=""></div><div class="">Simplified example:</div><div class=""><br class=""></div><div class="">protocol Animal {</div><div class=""> var hasEars: Bool { get }</div><div class=""> func grow()</div><div class="">}</div><div class=""><br class=""></div><div class=""><div class="">protocol Plant {</div><div class=""> var isGreen: Bool { get }</div><div class=""> func grow()</div><div class="">}</div><div class=""><br class=""></div><div class="">protocol LivingThing = Plant | Animal // or a different syntax</div><div class=""><br class=""></div><div class="">LivingThing's is as follows</div><div class="">{</div><div class=""> func grow()</div><div class="">}</div></div></div></div></blockquote></span><blockquote type="cite" class=""><div class=""><span class=""><div dir="ltr" class=""><div class=""><div class=""><br class=""></div>-- <br class=""><div class="m_-7576891152844605977m_4684597058227267120gmail_signature"><div dir="ltr" class=""><span class=""><div style="line-height:1.15;margin-top:0pt;margin-bottom:0pt" class=""><span style="font-size:16px;font-family:arial;background-color:transparent;font-style:italic;vertical-align:baseline;white-space:pre-wrap" class="">Rex Fenley</span><span style="font-size:16px;font-family:arial;background-color:transparent;vertical-align:baseline;white-space:pre-wrap" class=""> </span><span style="font-size:11px;font-family:arial;color:rgb(153,153,153);background-color:transparent;vertical-align:baseline;white-space:pre-wrap" class="">|</span><span style="line-height:1.15;font-family:arial;color:rgb(153,153,153);background-color:transparent;vertical-align:baseline;white-space:pre-wrap" class=""> </span><span style="font-size:11px;font-family:arial;color:rgb(153,153,153);background-color:transparent;vertical-align:baseline;white-space:pre-wrap" class="">IOS DEVELOPER</span><br class=""></div></span><span class=""><br class=""><div style="line-height:1.15;margin-top:0pt;margin-bottom:0pt" class=""><span style="font-size:11px;font-family:arial;color:rgb(153,153,153);vertical-align:baseline;white-space:pre-wrap;background-color:transparent" class=""><img src="https://lh5.googleusercontent.com/xMgzw3JkFL3DLkdwyq0WxJzKs_XP57gVVCaBMvgi1FKCjSeue0xdx3JZeCWBlxN4KRHhHOfdvJbc1N-AjTwXcKIq4cjJg9H7iaFpQ8WbO4N3c9Y5dzi19cPOs_owPquuqw" width="250px;" height="53px;" style="border:none" class=""></span></div><div style="line-height:1.15;margin-top:0pt;margin-bottom:0pt" class=""><a href="https://www.remind.com/" style="text-decoration:none" target="_blank" class=""><span style="font-size:11px;font-family:arial;color:rgb(17,85,204);font-weight:bold;text-decoration:underline;vertical-align:baseline;white-space:pre-wrap;background-color:transparent" class="">Remind.com</span></a><span style="font-family:arial;vertical-align:baseline;white-space:pre-wrap;background-color:transparent" class=""> </span><span style="font-size:11px;font-family:arial;vertical-align:baseline;white-space:pre-wrap;background-color:transparent" class="">| </span><a href="http://blog.remind.com/" style="text-decoration:none" target="_blank" class=""><span style="font-size:11px;font-family:arial;color:rgb(17,85,204);text-decoration:underline;vertical-align:baseline;white-space:pre-wrap;background-color:transparent" class="">BLOG</span></a><span style="font-size:11px;font-family:arial;vertical-align:baseline;white-space:pre-wrap;background-color:transparent" class=""> | </span><a href="https://twitter.com/remindhq" style="text-decoration:none" target="_blank" class=""><span style="font-size:11px;font-family:arial;color:rgb(17,85,204);text-decoration:underline;vertical-align:baseline;white-space:pre-wrap;background-color:transparent" class="">FOLLOW US</span></a><span style="font-size:11px;font-family:arial;vertical-align:baseline;white-space:pre-wrap;background-color:transparent" class=""> | </span><span style="font-family:arial;vertical-align:baseline;white-space:pre-wrap;background-color:transparent" class=""> </span><span style="text-decoration:underline;font-size:11px;font-family:arial;color:rgb(17,85,204);vertical-align:baseline;white-space:pre-wrap;background-color:transparent" class=""><a href="https://www.facebook.com/remindhq" style="text-decoration:none" target="_blank" class="">LIKE US</a></span></div></span></div></div>
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