Renamed debug identifiers: line, function, file

Paul Hudson      @twostraws

Swift 2.1 and earlier used the "screaming snake case" symbols __FILE__, __LINE__, __COLUMN__, and __FUNCTION__, which automatically get replaced the compiler by the filename, line number, column number and function name where they appear.

From Swift 2.2, those old symbols have been replaced with #file, #line, #column and #function, which will be familiar to you if you've already used Swift 2.0's #available to check for iOS features. As the official Swift review says, it also introduced "a convention where # means invoke compiler substitution logic here."

Here’s how the debug identifiers in action from Swift 2.2 and later:

func printGreeting(name: String, repeat repeatCount: Int) {
    print("This is on line \(#line) of \(#function)")

    let upperName = name.uppercaseString

    for _ in 0 ..< repeatCount {
        print(upperName)
    }
}

printGreeting("Taylor", repeat: 5)

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Other changes in Swift 2.2…

• ++ and -- are deprecated
• Traditional C-style for loops are deprecated
• Comparing tuples
• Tuple splat syntax is deprecated
• More keywords can be used as argument labels
• Variable parameters have been deprecated
• Stringified selectors are deprecated
• Compile-time Swift version checking

Download all Swift 2.2 changes as a playground Link to Swift 2.2 changes

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