Something I Don't Like about Swift

It can be easily figured out that I like Swift very much from my activities, but nothing is perfect. However, this post is not about the disadvantages of Swift (it surely has), instead it’s more about some of my personal preference.

Firstly, I don’t like the fact that in closures you have to use self. to access class variables and functions. I understand there’s some advantage in doing so, but my argument is that when you use closures you would emotionally think them part of the currently class, thus they should be able to access class variables and functions, and technically they surely can, and the compiler is even able to tell you self is missing when you try to access it. So if I was designing it, I would put class as a teriary scope inside the closures, which means if we try to access a variable inside a closure, it firstly looks for definition inside the closure itself, then the function that defines the closure, then the class that contains the function and so on. There should be no technical problem in it, and as I said, I think it’s natural to use it in the way I described.

Another thing I don’t like is the way Swift handles range. If you write something like this:

for i in 1 ... self.last_loaded {
	self.items.removeLast()
}

You’ll have a fatal error if self.last_loaded is less than 1. Maybe it has something to do with NSRage in which length is unsigned, but it doesn’t make to much sense: NSRange is just a C struct, and Swift Range is part of a language feature. So I would assume it’s not due to the implementation, but is more about how it’s designed. In this case, even I really like the attempt Swift wants to be a “strict” language and I’m enjoying features like optional chaining, this fatal error is still too much for me. My point is, range can be an elegant language feature, but if dynamically making it may cause a fatal error and an if check needs to be put beforehand, it becomes useless in a lot of cases, which leads you to fall back to the traditional way:

for var i = 0; i < self.last_loaded; i++ {
	self.items.removeLast()
}

So my second opition is that Swift Range should return nil if it’s not a valid range.

Anyway I may talk about more about this topic in the future, but I won’t talk things like “how slow Swift is” due to the fact that Swift is based on Objective-C, which uses a dynamic message based runtime and is slower in some tasks than C++, and it’s exepcted to be slower than Objective-C. I’m sure Apple will be keep optimizing it and I don’t appreciate the attitude to be a whiner about it, instead I would talk about how I would like it if I was put in the designer shoes and I feel like this is much more enjoyable.

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