I have personally (ab)used this for the following:
class User {
var email: String
var firstName: String?
var lastName: String?
}
You have a list of users based on email, so last name is optional. In Swift
2.x, you can do:
users.sort({ $0.lastName < $1.lastName })
Now, you need to do:
users.sorted({
guard let firstName = $0.0.lastName else {
return true
}
guard let secondName = $0.1.lastName else {
return false
}
return firstName < secondName
})
Which aside from being a brain teaser how to properly maintain ordering when
$0.0's lastName != nil && $0.1's lastName == nil, adds additional few lines.
But I agree that it may come as confusing with Ints, etc. - with strings it
kind of makes sense since nil is like an empty string which is placed in front
of everything.
> On Aug 27, 2016, at 1:46 PM, Haravikk via swift-evolution
> <[email protected]> wrote:
>
>
>> On 27 Aug 2016, at 02:01, Kevin Ballard via swift-evolution
>> <[email protected] <mailto:[email protected]>> wrote:
>>
>> This change is going to have a HUGE impact for me. I use this sort of
>> comparison _all the time_ and find it incredibly useful, and have had
>> literally zero bugs caused by this. Surely I can't be the only one who uses
>> this. I am not looking forward to copying & pasting a reimplementation of
>> the comparison functions into every single project I work on.
>
> Can you give some examples as to how this will have such a huge impact? Now
> that we have the ?? operator it seems that this is fairly easy to replace:
>
> value < 5 // where value is of type Int?
>
> With:
>
> (value ?? 0) < 5
>
>
> The latter is completely clear what the behaviour of nil is.
>
> Also, you can still re-add the operators where you need them, ideally with as
> limited a type as possible so you can make sure that it's behaviour is well
> defined.
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