Looks good so far. Top-level functions:
#doSomething() ModuleName#doSomething() // is it a problem to distinguish modules and classes here? What about static/class functions? Any idea how to fit them into that scheme? -Thorsten > Am 28.12.2015 um 16:05 schrieb T.J. Usiyan via swift-evolution > <[email protected]>: > > Do things get any better if we combine the proposed changes and remove the > bare case? Begin function reference with some symbol (# here but it doesn't > matter), only use back tics to disambiguate keywords (which lines up with > their current use) and remove the unadorned case to avoid ambiguity. > > ```swift > class Foo { > func doSomething() { } > func doSomething(value: Int) { } > func sub > } > > let fn = Foo#doSomething // no longer allowed > let fn = Foo#doSomething() // okay > let fn2 = Foo#doSomething(_:) // okay > > // and > > let getRow = someMatrix#`subscript`(row:).get > > ``` > > > >> On Sun, Dec 27, 2015 at 10:40 PM, Douglas Gregor via swift-evolution >> <[email protected]> wrote: >> >>> On Dec 27, 2015, at 12:27 AM, Frederick Kellison-Linn via swift-evolution >>> <[email protected]> wrote: >>> >>> Given that someView.insertSubview(_:at:) can be correctly parsed, I would >>> strongly lean towards the no-backtick alternative mentioned at the end. I >>> feel as though the backticks end up looking very cluttered (particularly >>> when you get into the double-nested backticks), and it seems cleaner to be >>> able to reference a method as it was declared rather than having to add >>> extra syntax. >>> >>> In reference to the issues noted with this approach: >>> >>> IMO, there is already enough syntactic difference between getters/setters >>> and normal methods to justify requiring a different syntax to reference >>> them. For instance, the # syntax could be used so that, >>> button.currentTitle.get would reference Optional<String>.get, and >>> button.currentTitle#get would reference the getter. Or, >>> button.`currentTitle.get` could reference the getter (i.e. backticks are >>> only required in cases that are ambiguous). >>> >>> I also think it is reasonable to require that in the case of a method with >>> no arguments such as set.removeAllElements, the programmer be expected to >>> know the difference between the expression with and without the trailing >>> parenthesis. After all, that distinction already exists in the language, >>> and would not disappear with this proposed addition. If a parallel syntax >>> for referencing methods with no arguments is strongly desired, perhaps >>> something such as set.removeAllElements(:), set#removeAllElements(), or >>> similar could be used, though I think that the present system for >>> referencing these methods is sufficient. >>> >>> Are there other obvious reasons why this alternative wouldn’t work? I think >>> it is the cleanest of the alternatives and avoids littering the code with >>> backticks. >> >> Not having the back-ticks means that you will need to use contextual type >> information to disambiguate the zero-parameter case from other cases. For >> example: >> >> class Foo { >> func doSomething() { } >> func doSomething(value: Int) { } >> } >> >> let fn = Foo.doSomething // ambiguous >> let fn2 = Foo.doSomething(_:) // okay >> let fn3: (Foo) -> () -> Void = Foo.doSomething // okay >> let fn3: (Foo) -> (Int) -> Void = Foo.doSomething // okay >> >> My general complaint with the “drop the backticks” approach is that it >> doesn’t solve the whole problem. Sure, it solves 95% of the problem with a >> little less syntax, but now you need to invent yet another mechanism to >> handle the other cases (#set, contextual type disambiguation, etc)… which >> seems inconsistent to me. >> >> - Doug >> >> >>>> On Dec 26, 2015, at 11:22 PM, Douglas Gregor via swift-evolution >>>> <[email protected]> wrote: >>>> >>>> Hi all, >>>> >>>> Here’s a proposal draft to allow one to name any function in Swift. In >>>> effect, it’s continuing the discussion of retrieving getters and setters >>>> as functions started by Michael Henson here: >>>> >>>> >>>> https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20151207/002168.html >>>> >>>> the proposal follows, and is available here as well: >>>> >>>> >>>> https://github.com/DougGregor/swift-evolution/blob/generalized-naming/proposals/0000-generalized-naming.md >>>> >>>> Comments appreciated! >>>> >>>> Generalized Naming for Any Function >>>> >>>> Proposal: SE-NNNN >>>> Author(s): Doug Gregor >>>> Status: Awaiting Review >>>> Review manager: TBD >>>> Introduction >>>> >>>> Swift includes support for first-class functions, such that any function >>>> (or method) can be placed into a value of function type. However, it is >>>> not possible to specifically name every function that is part of a Swift >>>> program---one cannot provide the argument labels when naming a function, >>>> nor are property and subscript getters and setters referenceable. This >>>> proposal introduces a general syntax that allows one to name anything that >>>> is a function within Swift in an extensible manner. >>>> >>>> Swift-evolution thread: Michael Henson started a thread about the >>>> getter/setter issue here, continued here. See the Alternatives considered >>>> section for commentary on that discussion. >>>> >>>> Motivation >>>> >>>> It's fairly common in Swift for multiple functions or methods to have the >>>> same "base name", but be distinguished by parameter labels. For example, >>>> UIView has three methods with the same base name insertSubview: >>>> >>>> extension UIView { >>>> func insertSubview(view: UIView, at index: Int) >>>> func insertSubview(view: UIView, aboveSubview siblingSubview: UIView) >>>> func insertSubview(view: UIView, belowSubview siblingSubview: UIView) >>>> } >>>> When calling these methods, the argument labels distinguish the different >>>> methods, e.g., >>>> >>>> someView.insertSubview(view, at: 3) >>>> someView.insertSubview(view, aboveSubview: otherView) >>>> someView.insertSubview(view, belowSubview: otherView) >>>> However, when referencing the function to create a function value, one >>>> cannot provide the labels: >>>> >>>> let fn = someView.insertSubview // ambiguous: could be any of the three >>>> methods >>>> In some cases, it is possible to use type annotations to disambiguate: >>>> >>>> let fn: (UIView, Int) = someView.insertSubview // ok: uses >>>> insertSubview(_:at:) >>>> let fn: (UIView, UIView) = someView.insertSubview // error: still >>>> ambiguous! >>>> To resolve the latter case, one must fall back to creating a closure: >>>> >>>> let fn: (UIView, UIView) = { view, otherView in >>>> button.insertSubview(view, otherView) >>>> } >>>> which is painfully tedious. A similar workaround is required to produce a >>>> function value for a getter of a property, e.g., >>>> >>>> extension UIButton { >>>> var currentTitle: String? { ... } >>>> } >>>> >>>> var fn: () -> String? = { () in >>>> return button.currentTitle >>>> } >>>> One additional bit of motivation: Swift should probably get some way to >>>> ask for the Objective-C selector for a given method (rather than writing a >>>> string literal). The argument to such an operation would likely be a >>>> reference to a method, which would benefit from being able to name any >>>> method, including getters and setters. >>>> >>>> Proposed solution >>>> >>>> Swift currently has a back-tick escaping syntax that lets one use keywords >>>> for names, which would otherwise fail to parse. For example, >>>> >>>> func `try`() -> Bool { ... } >>>> declares a function named try, even though try is a keyword. I propose to >>>> extend the back-tick syntax to allow compound Swift names (e.g., >>>> insertSubview(_:aboveSubview:)) and references to the accessors of >>>> properties (e.g., the getter for currentTitle). Specifically, >>>> >>>> Compound names can be written entirely within the back-ticks, e.g., >>>> >>>> let fn = someView.`insertSubview(_:at:)` >>>> let fn1 = someView.`insertSubview(_:aboveSubview:)` >>>> The same syntax can also refer to initializers, e.g., >>>> >>>> let buttonFactory = UIButton.`init(type:)` >>>> Getters and setters can be written using dotted syntax within the >>>> back-ticks: >>>> >>>> let specificTitle = button.`currentTitle.get` // has type () -> String? >>>> let otherTitle = UIButton.`currentTitle.get` // has type (UIButton) -> () >>>> -> String? >>>> let setTintColor = button.`tintColor.set` // has type (UIColor!) -> () >>>> The same syntax works with subscript getters and setters as well, using >>>> the full name of the subscript: >>>> >>>> extension Matrix { >>>> subscript (row row: Int) -> [Double] { >>>> get { ... } >>>> set { ... } >>>> } >>>> } >>>> >>>> let getRow = someMatrix.`subscript(row:).get` // has type (Int) -> () -> >>>> [Double] >>>> let setRow = someMatrix.`subscript(row:).set` // has type (Int) -> >>>> ([Double]) -> () >>>> If we introduce property behaviors into Swift, the back-tick syntax could >>>> also be used to refer to behaviors, e.g., accessing the lazy behavior of a >>>> property: >>>> >>>> self.`myProperty.lazy`.clear() >>>> Base names that are meaningful keywords (init and subscript) can be >>>> escaped with a nested pair of back-ticks: >>>> >>>> extension Font { >>>> func `subscript`() -> Font { >>>> // return the subscript version of the given font >>>> } >>>> } >>>> >>>> let getSubscript = font.``subscript`()` // has type () -> Font >>>> The "produce the Objective-C selector for the given method" operation will >>>> be the subject of a separate proposal. However, here is one possibility >>>> that illustrations how it uses the proposed syntax here: >>>> >>>> let getter: Selector = objc_selector(NSDictionary.`subscript(_:).get`) // >>>> produces objectForKeyedSubscript: >>>> let setter: Selector = objc_selector(NSDictionary.`subscript(_:).set`) // >>>> produces setObject:forKeyedSubscript: >>>> Impact on existing code >>>> >>>> This is a purely additive feature that has no impact on existing code. The >>>> syntactic space it uses is already present, and it merely extends the use >>>> of back-ticks from storing a single identifier to more complex names. >>>> >>>> Alternatives considered >>>> >>>> Michael Henson proposed naming getters and setters using # syntax followed >>>> by get or set, e.g., >>>> >>>> let specificTitle = button.currentTitle#get >>>> The use of postfix # is a reasonable alternative here, and more >>>> lightweight than two back-ticks for the simple getter/setter case. The >>>> notion could be extended to allow argument labels for functions, discussed >>>> here. The proposals in that discussion actually included type annotations >>>> as well, but the syntax seems cleaner---and more directly focused on >>>> names---without them, e.g.,: >>>> >>>> let fn = someView.insertSubview#(_:at:) >>>> which works. I didn't go with this syntax because (1) it breaks up Swift >>>> method names such as insertSubview(_:at:)with an # in the middle, and (2) >>>> while useful, this feature doesn't seem important enough to justify >>>> overloading #further. >>>> >>>> Joe Groff notes that lenses are a better solution than manually retrieving >>>> getter/setter functions when the intent is to actually operate on the >>>> properties. That weakens the case this proposal makes for making >>>> getters/setters available as functions. However, it doesn't address the >>>> general naming issue or the desire to retrieve the Objective-C selector >>>> for a getter/setter. >>>> >>>> Can we drop the back-ticks? It's very tempting to want to drop the >>>> back-ticks entirely, because something like >>>> >>>> let fn = someView.insertSubview(_:at:) >>>> can be correctly parsed as a reference to insertSubview(_:at:). However, >>>> it breaks down at the margins, e.g., with getter/setter references or >>>> no-argument functions: >>>> >>>> extension Optional { >>>> func get() -> T { return self! } >>>> } >>>> >>>> let fn1 = button.currentTitle.get // getter or Optional<String>.get? >>>> let fn2 = set.removeAllElements() // call or reference? >>>> >>>> >>>> - Doug >>>> >>>> >>>> _______________________________________________ >>>> swift-evolution mailing list >>>> [email protected] >>>> https://lists.swift.org/mailman/listinfo/swift-evolution >>> _______________________________________________ >>> swift-evolution mailing list >>> [email protected] >>> https://lists.swift.org/mailman/listinfo/swift-evolution >> >> >> >> _______________________________________________ >> swift-evolution mailing list >> [email protected] >> https://lists.swift.org/mailman/listinfo/swift-evolution > > > _______________________________________________ > swift-evolution mailing list > [email protected] > https://lists.swift.org/mailman/listinfo/swift-evolution
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