Multiple variadic parameters in functions

Paul Hudson      @twostraws

SE-0284 introduced the ability to have functions, subscripts, and initializers use multiple variadic parameters as long as all parameters that follow a variadic parameter have labels. Before Swift 5.4, you could only have one variadic parameter in this situation.

So, with this improvement in place we could write a function that accepts a variadic parameter storing the times goals were scored during a football match, plus a second variadic parameter scoring the names of players who scored:

import Foundation

func summarizeGoals(times: Int..., players: String...) {
    let joinedNames = ListFormatter.localizedString(byJoining: players)
    let joinedTimes = ListFormatter.localizedString(byJoining: times.map(String.init))

    print("\(times.count) goals where scored by \(joinedNames) at the follow minutes: \(joinedTimes)")
}

To call that function, provide both sets of values as variadic parameters, making sure that all parameters after the first variadic are labeled:

summarizeGoals(times: 18, 33, 55, 90, players: "Dani", "Jamie", "Roy")

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Other changes in Swift 5.4…

• Improved implicit member syntax
• Local functions now support overloading
• Creating variables that call a function of the same name
• Result builders
• Property wrappers are now supported for local variables
• Packages can now declare executable targets

Download all Swift 5.4 changes as a playground Link to Swift 5.4 changes

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