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When should you use shorthand parameter names?

Paul Hudson    @twostraws   

Updated for Xcode 13.2

When working with closures, Swift gives us a special shorthand parameter syntax that makes it extremely concise to write closures. This syntax automatically numbers parameter names as $0, $1, $2, and so on – we can’t use names such as these in our own code, so when you see them it’s immediately clear these are shorthand syntax for closures.

As for when you should use them it’s really a big “it depends”:

  1. Are there many parameters? If so, shorthand syntax stops being useful and in fact starts being counterproductive – was it $3 or $4 that you need to compare against $0 Give them actual names and their meaning becomes clearer.
  2. Is the function commonly used? As your Swift skills progress, you’ll start to realize that there are a handful – maybe 10 or so – extremely common functions that use closures, so others reading your code will easily understand what $0 means.
  3. Are the shorthand names used several times in your method? If you need to refer to $0 more than maybe two or three times, you should probably just give it a real name.

What matters is that your code is easy to read and easy to understand. Sometimes that means making it short and simple, but not always – choose shorthand syntax on a case by case basis.

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