More on supporting repeating initializers with closures

[CTMacUser (Daryle Walker)]

(Saw the original thread while researching something else.)

Continuing the discussion from Support repeating initializers with closures not just values:

@Moximillian

The thing that bit me in the past, was doing something like this:

let layers = Array(repeating: CALayer(), count: 5)

It took awfully long time to figure out why it wasn't working (single layer, not 5 different layers).
And once I understood it, it baffled me, why the Array() didn't have an initializer that allowed me to do the thing I intended.

It took a lot of detours in whiles and for-in loops, before stumbling on map... Yes, map would be obvious choice for those who spend their daily lives in flatmap land, but it's not obvious to those who are learning the basics.

Maybe a better parameter name could help:

extension RangeReplaceableCollection {

    /// Creates a collection with the given number of elements, each created by
    /// separate calls to the given closure.
    ///
    /// - Precondition: `count >= 0`.
    ///
    /// - Parameter count: The number of elements to create.
    /// - Parameter body: The closure to call each time to return an initial
    ///   element.
    /// - Postcondition: The collection has `count` elements, resulting from
    ///   `count` calls to `body`.
    ///
    /// - Complexity: O(*n*), where *n* is the length of the collection.
    public init(distinctCallCount count: Int, of body: () throws -> Element) rethrows {
        self.init()
        reserveCapacity(count)
        for _ in 0..<count {
            append(try body())
        }
    }

}

I don't think this needs to be a customization point.