100% agree with everything. A custom operator is a good idea for operations that are actually frequent: once you learn what it means, it really helps reduce noise in code and improve readability. But forced unwrapping is something that's intended to be used sparsely.
Elviro > Il giorno 30 giu 2017, alle ore 10:15, Víctor Pimentel Rodríguez via > swift-evolution <swift-evolution@swift.org> ha scritto: > > On Fri, Jun 30, 2017 at 7:24 AM, Brent Royal-Gordon via swift-evolution > <swift-evolution@swift.org <mailto:swift-evolution@swift.org>> wrote: >> On Jun 27, 2017, at 10:16 AM, Erica Sadun via swift-evolution >> <swift-evolution@swift.org <mailto:swift-evolution@swift.org>> wrote: >> >> Using an operator to provide feedback on the context of a failed unwrap has >> become a commonly implemented approach in the Swift developer Community. >> What are your thoughts about adopting this widely-used operator into the >> standard library? >> >> guard !lastItem.isEmpty else { return } >> let lastItem = array.last !! "Array must be non-empty" >> >> Details here: >> https://gist.github.com/erica/423e4b1c63b95c4c90338cdff4939a9b >> <https://gist.github.com/erica/423e4b1c63b95c4c90338cdff4939a9b> >> >> Thank you for your thoughtful feedback, -- E > > Finally found a few minutes to read this thread. > > I'm a big fan of the `Never`-based approach. (I was before, but I am more so > now.) Here are the points I can see in its favor: > > 1. It is extremely clear about what's happening—`!!` is another random > operator to learn, but `fatalError(_:)` or `preconditionFailure(_:)` are > fairly self-explanatory, and `??` is something you might already be using. > > 2. It allows you to control the optimization behavior by using `fatalError`, > `preconditionFailure`, or `assertionFailure` as desired. > > 3. If we later change `throw` from being a statement to being a > `Never`-returning expression, you could use `throw` on the right-hand side of > `??`. > > 4. It supports other `Never`-returning operations, like `abort()` or > `exit(_:)` or your custom `usage()` function, on the right side of `??`. > > 5. It supports file-and-line error reporting without having to add any new > features; `!!` could not do this because an operator can't have extra, > defaulted parameters to carry the file and line. > > 6. It harmonizes with the eventual idea of making `Never` a universal bottom > type, but we don't actually have to implement that today, because we can just > overload `??` for now. > > Against these advantages, the only one I can see for `!!` is that it is > terse. Terseness is good, especially for a feature which is competing with > the single-character postfix `!` operator, but I can't help but be drawn to > the flexibility and power of `??` with a `Never` expression on the right-hand > side. > > +1 to everything. > > If terseness is the only clear advantage of a new operator that is meant to > be used sparsely, it's clear to me that the ?? Never form is better for the > Swift community as a whole. > > -- > Víctor Pimentel > _______________________________________________ > swift-evolution mailing list > swift-evolution@swift.org <mailto:swift-evolution@swift.org> > https://lists.swift.org/mailman/listinfo/swift-evolution > <https://lists.swift.org/mailman/listinfo/swift-evolution>
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