[swift-evolution] [Review] SE-0024 "Optional Value Setter `??=`"
stephen.celis at gmail.com
Wed Feb 17 09:43:58 CST 2016
> On Feb 13, 2016, at 7:10 AM, James Campbell via swift-evolution <swift-evolution at swift.org> wrote:
> One common case could be for a error catching, consider this:
> let object = try? UnsupportedMessage(text: "James", type:.Text, date:NSDate()) ?? FailedObject()
> var object = try? Message(text: "James", type:.Text, date:NSDate())
> object ??= UnsupportedMessage()
> Why would we need this? I have a chat application where if it gets a message it doesn't understand it will throw an error. In the past I would handle this errors by returning nil like so. However we want to communicate to the user that they missing content by vending a UnsupportedMessage object which shows the UI to prompt them to upgrade.
> If the object being constructed has a lot of variables then it could be lost off the side of the screen. I feel ??= is more concise in this case.
If conciseness is your goal, isn't "??" more concise here? (It's a single line—rather than two—and fewer characters.)
If you're worried about line length and/or readability, have you considered using a newline to break the logic up?
let object = try? UnsupportedMessage(text: "James", type:.Text, date:NSDate())
- the result isn't mutable and
- the result isn't optional
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