<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div>I like the idea of ‘named parameterised properties’, but I don't see it happening for Swift 3, which is unfortunate since it would tidy up quite a few APIs.</div><div id="AppleMailSignature">If this feature does get added, updating getter functions to them would be a non-breaking change, so maybe it would be possible to deprecate setImage(_:for:) and have a long trasition period.</div><div id="AppleMailSignature"><br></div><div id="AppleMailSignature">The idea of using subscripts for this kind of property is interesting, but currently they don't show up in autocomplete, so working with labelled subscripts is tricky.</div><div id="AppleMailSignature"><br></div><div id="AppleMailSignature">This does raise the question of where to draw the line with subscripts - should they only be used where the container itself is the base name of the ‘function’? But if this is the case:</div><div id="AppleMailSignature"><br></div><div id="AppleMailSignature">self.items[0 ... 1] //good</div><div id="AppleMailSignature"><br></div><div id="AppleMailSignature">self.item[0] //good</div><div id="AppleMailSignature"><br></div><div id="AppleMailSignature">self.items[0] //bad, reads as ‘items 0’, not the grammatical term ‘item 0’</div><div id="AppleMailSignature"><br></div><div id="AppleMailSignature">You could say we're already misusing them.</div><div><br>On 11 Jul 2016, at 23:00, Tim Vermeulen <<a href="mailto:tvermeulen@me.com">tvermeulen@me.com</a>> wrote:<br><br></div><blockquote type="cite"><div><meta http-equiv="Content-Type" content="text/html charset=utf-8">Slightly related to this, I would really love to have non-subscript parameterized properties. It would allow us to write<div class=""><br class=""></div><div class=""><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #4f8187" class="">button</span><span style="font-variant-ligatures: no-common-ligatures" class="">.image(</span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">for</span><span style="font-variant-ligatures: no-common-ligatures" class="">: .normal) = </span><span style="font-variant-ligatures: no-common-ligatures; color: #4f8187" class="">image</span></div></div><div class=""><br class=""></div><div class="">instead of</div><div class=""><br class=""></div><div class=""><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(79, 129, 135);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">button</span><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class="">.</span><span style="font-variant-ligatures: no-common-ligatures; color: #3e1e81" class="">setImage</span><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class="">(</span><span style="font-variant-ligatures: no-common-ligatures" class="">image</span><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class="">, </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">for</span><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class="">: .</span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">normal</span><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class="">)</span></div></div><div class=""><br class=""></div><div class="">The same can be achieved through subscripts, but it’s not always as nice. It would bring subscripts and computed properties closer together, which also seems to be the goal of your proposal. Perhaps the two ideas could be combined?<br class=""><div class=""><br class=""></div><div class="">> Subscripts are a hybrid of properties and functions, since they have a parameter list, as well as getters and setters, so use of either symbol will be unusual in this case.<br class="">> <br class="">> However, I think a colon is more suitable, since it implies the possibility to set the value.<br class="">> <br class="">> <br class="">> In the future, if we add throwing getters/ setters:<br class="">> <br class="">> subscript(_ position: Int) ->Element {<br class="">> get {<br class="">> return …<br class="">> }<br class="">> throwing set {<br class="">> …<br class="">> }<br class="">> }<br class="">> <br class="">> Should this require ‘throws ->Element’? Using a colon also removes this potentially confusing case.<br class="">> <br class="">> <br class="">> Thoughts?<br class="">> <br class="">> <br class="">><span class="Apple-converted-space"> </span>
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