> On Jan 12, 2018, at 12:14 AM, Nate Cook via swift-evolution
> <swift-evolution@swift.org> wrote:
>
>
>> On Jan 12, 2018, at 12:15 AM, Chris Eidhof via swift-evolution
>> <swift-evolution@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`.
That’s a good one. Similar to bit flipping which Apple calls inverting.
“The bitwise NOT operator (~) inverts all bits in a number:”
I was thinking `flip` for this function but then I actually don’t think this
extension is a good idea in the standard library :(
Should we also have a mutating extension for the `NOT` operator? Probably no.
If people need it, they can add it and call it toggle, invert, flip, reverse,
negate or what ever they want.
It’s a slippery slope because it makes me want to have something like `not()`
added to the library. I don’t think it’s worth it.
>
> 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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