<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=""><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; line-height: 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="">For "build via factory method", why not Factory or Manufacturer?</span></div></blockquote><div><br class=""></div><div>I don’t think that accurately portrays this case. The Factory and Factory Method patterns are quite different. We are talking about factory methods that create instances of the conforming type itself with a parameter of the type described by the protocol. We are not discussing a type that is a factory producing instances of other types. </div><div><br class=""></div><div>I am not convinced that distinct conventions for the initializer case and the factory method case are worthwhile. They are two mechanisms for taking an instance of one type and getting back an instance of another type. In a significant sense the use of an initializer or a factory method is an "implementation detail" of the protocol.<span class="Apple-tab-span" style="white-space:pre"> </span></div><div><br class=""></div><div>It is probably better to form protocol naming conventions around the high level purpose of the protocol and not how that purpose is fulfilled by the protocol.</div><br class=""><blockquote type="cite" class=""><div class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: 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;">For "can be converted to", I can understand wanting to stay away from Convertible - but we should avoid it for round-trip conversions as well. To convert is the action of changing from one form to another (water into wine), without regards to changing back. Convertible is a property, and thus often means you are able to change from one form to another repeatedly. But there are edge cases for both conditions.</div></blockquote><div><br class=""></div><div>I am definitely not in love with Convertible. It does seem to have a lot of potential for confusion exhibited by its use for different senses in the standard library. Do you have any suggestions of this?</div><br class=""><blockquote type="cite" class=""><div class=""><div class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: 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;"><div class=""><br class=""></div><div class="">Converters to string form are difficult as there is a certain amount of presentation. An NSDate needs to understand a locale, a floating point number or currency may have desired display rules beyond a locale. This is I suspect why there is a CustomDebugStringConvertible variant that possibly exposes more/different info.</div><div class=""><br class=""></div><div class="">-DW</div><div class=""><br class=""><div class=""><br class=""><div class=""><blockquote type="cite" class=""><div class="">On Dec 15, 2015, at 5:30 PM, Erica Sadun 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 class="" 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;"><b class="">Terms currently on the table:</b></div><div class="" 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;"><div class=""><ul class=""><li class="">can be initialized from:<span class="Apple-converted-space"> </span><font face="Courier" class="">Instantiable, Initializable, Establishable</font></li><li class="">can build via factory method:<span class="Apple-converted-space"> </span><font face="Courier" class="">Creatable, Building, Producer/Producing, Establishable</font></li><li class="">can be converted to:<span class="Apple-converted-space"> </span><font face="Courier" class="">Representable, Expressible, Presentable, Projectable</font></li><li class="">can be represented as and instantiated by:<span class="Apple-converted-space"> </span><font face="Courier" class="">Convertible, Representable</font></li></ul></div></div><div class="" 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;"><br class=""></div><div class="" 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;">I'm going to courteously disagree with Brent ("I actually think `Representable` better implies two-way than `Convertible` does"). Here's my reasoning. <b class="">Convertible</b><span class="Apple-converted-space"> </span>implies a commutative or two-way relation. For example, a convertible car can be converted to a sedan style or an open style. A convertible sofa can act as a bed or a sofa. Convertible suggests<span class="Apple-converted-space"> </span><b class="">a R b</b><span class="Apple-converted-space"> </span>as well as<b class=""><span class="Apple-converted-space"> </span>b R a</b>. The word means to change into a different form and be used in a different way. </div><div class="" 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;"><br class=""></div><div class="" 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;">To<span class="Apple-converted-space"> </span><b class="">represent</b><span class="Apple-converted-space"> </span>means to serve as or to take the place of by accruing characteristics or qualities. This suggests that<span class="Apple-converted-space"> </span><b class="">a R b</b><span class="Apple-converted-space"> </span>is<span class="Apple-converted-space"> </span><i class="">not</i> the same as<span class="Apple-converted-space"> </span><b class="">b R a</b>. My lawyer can represent my legal interests but I cannot represent my lawyer in court. </div><div class="" 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;"><br class=""></div><div class="" 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;">To<span class="Apple-converted-space"> </span><b class="">create</b> means to produce something new and cause it to exist. This is semantically distant from<span class="Apple-converted-space"> </span><b class="">initializing</b>. The current (badly named) IntegerLiteralConvertible means "a conforming construct can use an integer literal to establish an instance of itself". There are, as Matthew points out two tasks that might arise through protocols: the creation of an instance through a factory method and the creation an instance by passing a separate type to an initializer.</div><div class="" 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;"><br class=""></div><div class="" 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;">The latter case is what we see throughout and commonly in the current Swift standard library:<span class="Apple-converted-space"> </span><font face="Courier" class="">A.init(b) -> a</font>. Of the words that have been brought up so far, to<span class="Apple-converted-space"> </span><b class="">instantiate</b><span class="Apple-converted-space"> </span>and to<span class="Apple-converted-space"> </span><b class="">initialize</b><span class="Apple-converted-space"> </span>are the only two that describe this task. I do not believe this is well described as conversion.</div><div class="" 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;"><br class=""></div><div class="" 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;">I assume the factory style is<span class="Apple-converted-space"> </span><font face="Courier" class="">A.staticMethod(...) -> a</font>. In such case, I've collected your suggestions plus a few others above.</div><div class="" 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;"><br class=""></div><div class="" 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;">Of these, I most prefer initializable (<font face="Courier" class="">DoubleLiteralInitializable</font>), convertible (<font face="Courier" class="">RawConvertible</font>,<span class="Apple-converted-space"> </span><font face="Courier" class="">StringLiteralConvertible</font>), and representable (<font face="Courier" class="">CustomStringRepresentable</font>). I have no particular feelings about factory methods at this time.</div><div class="" 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;"><br class=""></div><div class="" 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;">Finally, I grabbed the following from a quick search of release notes, just to get a sense that protocol renaming does happen:</div><div class="" 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;"><ul class=""><li class="">LogicValue became BooleanType</li><li class="">Printable and DebugPrintable became CustomStringConvertible, CustomDebugStringConvertible</li><li class="">ExtensibleCollectionType was folded into RangeReplaceableCollectionType</li></ul></div><div class="" 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;"><br class=""></div><div class="" 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;">-- Erica</div><div class="" 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;"><br class=""></div><br class="" 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;"><div class="" 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;"><blockquote type="cite" class=""><div class="">On Dec 15, 2015, at 4:40 PM, Matthew Johnson <<a href="mailto:matthew@anandabits.com" class="">matthew@anandabits.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class="">I really like Creatable for the first as it is general enough to handle initializers an factory methods. Great idea! Alternatively, we could use that for a fourth category covering factory methods and stick with Initializable for the first case.<br class=""><br class=""><blockquote type="cite" class="">On Dec 15, 2015, at 5:30 PM, Brent Royal-Gordon <<a href="mailto:brent@architechies.com" class="">brent@architechies.com</a>> wrote:<br class=""><br class=""><blockquote type="cite" class=""><blockquote type="cite" class=""><blockquote type="cite" class="">resentable is probably a lot better than CustomStringRepresentationExpressible<br class=""></blockquote><br class="">Representable is what I would have used if I wasn't trying to make a minimal change or if RawRepresentable didn't already use it for bidirectional conversion, so I agree that it is better than both Expressible and Projectable.<br class=""></blockquote><br class="">Let's run with the idea that everything is up for grabs and that better names will better serve the developer community in the long run. In such a case, if the core naming patterns were established as Convertible for bidirectional conversion, would RawConvertible be such a bad thing?<br class=""></blockquote><br class="">I actually think `Representable` better implies two-way than `Convertible` does. A representation is a way of expressing something in a different form; a conversion is a specific act of transforming one thing to another. To me, the former sounds more like a round trip than the latter.<br class=""><br class="">So I suggest:<br class=""><br class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>protocol IntegerLiteralInitializable {...} // or maybe ‘Creatable’, to cover the factory method case?<br class=""><span class="Apple-tab-span" style="white-space: pre;"> </span><br class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>protocol RawRepresentable {…}<br class=""><span class="Apple-tab-span" style="white-space: pre;"> </span><br class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>protocol CustomStringConvertible {…}<br class=""><br class=""></blockquote><br class=""><br class=""><br class=""></div></div></blockquote></div><br class="" 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; 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