[swift-evolution] [pitch] adding toggle to Bool

[Adrian Zubarev]

All I meant is that it’s usage should fade, which is my personal opinion. That said, I didn’t meant to say it should be removed or something. ;)


Am 12. Januar 2018 um 20:54:16, Alejandro Martinez (alexito4 at gmail.com) schrieb:

I wouldn't go as far as to ask to fade out ! but in all my code I end  
up doing == false just for readability. That ! knows who to hide  
himself too well :P  

On Fri, Jan 12, 2018 at 10:13 AM, Adrian Zubarev via swift-evolution  
<swift-evolution at swift.org> wrote:  
> I’m not sure if this would be considered or not, but I would like if the  
> negation operator `!` would fade out.  
>  
> If this is ever going to a review then I’d suggest that we add a pair of  
> functions, one mutating and the other non-mutating.  
>  
> extension Bool {  
> mutating func invert() {  
> self = !self  
> }  
>  
> func inverted() {  
> return !self  
> }  
> }  
>  
> I’d rather use `inverted` instead of `!` because of the readability this  
> function provides.  
>  
> if !items.contains(item) { ... }  
>  
> if items.contains(item).inverted() { ... }  
>  
> ——  
>  
> I personally have some other extensions like:  
>  
> extension Bool {  
> @discardableResult  
> func whenTrue<T>(execute closure: () throws -> T) rethrows -> T? {  
> if self { return try closure() }  
> return nil  
> }  
>  
> @discardableResult  
> func whenFalse<T>(execute closure: () throws -> T) rethrows -> T? {  
> if !self { return try closure() }  
> return nil  
> }  
> }  
>  
> But this is more a personal preference.  
>  
> ——  
>  
> That said, if the community is fine with the `invert/inverted` pair then I’d  
> say go for it ;)  
>  
> Am 12. Januar 2018 um 09:14:22, Nate Cook via swift-evolution  
> (swift-evolution at swift.org) schrieb:  
>  
>  
> On Jan 12, 2018, at 12:15 AM, Chris Eidhof via swift-evolution  
> <swift-evolution at swift.org> wrote:  
>  
> Hey SE!  
>  
> When we have a bunch of nested structs:  
>  
> struct Sample {  
> var bar: Bar  
> }  
>  
> struct Bar {  
> var show: Bool  
> }  
>  
> var foo = Sample(bar: Bar(show: false))  
>  
> It can be repetitive to toggle a deeply nested boolean:  
>  
> foo.bar.show = !foo.bar.show // duplication  
>  
> I sometimes add a `toggle` extension on `Bool`  
>  
> extension Bool {  
> mutating func toggle() {  
> self = !self  
> }  
> }  
>  
> This allows you to write the same code without duplication, and makes the  
> intent clearer:  
>  
> foo.bar.show.toggle()  
>  
>  
> I like it!  
>  
> In other languages, I don't think the `toggle` would make as much sense, but  
> the mutable self makes this very useful.  
>  
> After I posted it on Twitter, it turns out I'm not the only one:  
> https://twitter.com/PublicExtension/status/730434956376346624  
>  
> I would have gone straight to a proposal, but I think we can do some  
> bikeshedding about the name of `toggle`?  
>  
>  
> Another verb that could work is `invert`.  
>  
> The `!` operator that does this is the negation operator, but I think  
> `negate` could sound to some like "make this false" rather than toggling.  
>  
> Nate  
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>  
>  
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>  



--  
Alejandro Martinez  
http://alejandromp.com  
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