where clauses on contextually generic declarations 관련

HACKING WITH SWIFT

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What's new in Swift?

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where clauses on contextually generic declarations | Changes in Swift 5.3

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where clauses on contextually generic declarations

Available from Swift 5.3

SE-0267 (apple/swift-evolution) introduced the ability to attach a where clause to functions inside generic types and extensions.

For example, we could start with a simple Stack struct that let us push and pop values from a private array:

struct Stack<Element> {
    private var array = [Element]()

    mutating func push(_ obj: Element) {
        array.append(obj)
    }

    mutating func pop() -> Element? {
        array.popLast()
    }
}

Using SE-0267, we could add a new sorted() method to that stack, but only for times when the elements inside the stack conform to Comparable:

extension Stack {
    func sorted() -> [Element] where Element: Comparable {
        array.sorted()
    }
}

Other Changes in Swift 5.3

Multi-pattern catch clauses | Changes in Swift 5.3

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Multi-pattern catch clauses

Multiple trailing closures | Changes in Swift 5.3

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Multiple trailing closures

Synthesized Comparable conformance for enums | Changes in Swift 5.3

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Synthesized Comparable conformance for enums

self is no longer required in many places | Changes in Swift 5.3

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self is no longer required in many places

Type-based program entry points | Changes in Swift 5.3

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Type-based program entry points

Enum cases as protocol witnesses | Changes in Swift 5.3

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Enum cases as protocol witnesses

Refined didSet semantics | Changes in Swift 5.3

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Refined didSet semantics

A new Float16 type | Changes in Swift 5.3

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A new Float16 type

Swift Package Manager gains binary dependencies, resources, and more | Changes in Swift 5.3

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Swift Package Manager gains binary dependencies, resources, and more

Download Swift 5.3 playground