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## 2015-04-08

### Swift Code Library: functions minmax and clippedMinMax

You are probably well aware of the functions:

func min<T : Comparable>(x: T, y: T) -> T
func max<T : Comparable>(x: T, y: T) -> T

When implementing functions that need a result in order we need to call both functions like:

let a = max(x, y)
let b = min(x, y)

Which is a bit laborious given that Swift has tuples that can be used to return values.

It would be nice to be able to write this as:

let (a, b) = minmax(x, y)

This is of course not all that difficult, I use the following implementation:

func minmax<T: Comparable>(first: T, second: T) -> (min: T, max: T) {
let rmin = min(first, second)
let rmax = max(first, second)
return (rmin, rmax)
}

In addition, often I also have to safeguard the return values against minimum and maximum values. For that I use the following function:

func clippedMinMax<T: Comparable>(lowLimit: T, first: T, second: T, highLimit: T) -> (min: T, max: T) {
let amin = max(lowLimit, min(highLimit, first))
let amax = min(highLimit, max(lowLimit, second))
return minmax(amin, amax)
}

This function can be called for example as follows:

let (a, b) = clippedMinMax(0, x, y, 100)

The function guarantees me that 'a' and 'b' will be in order, and that neither 'a' nor 'b' will be lower than 0 or higher than 100.

PS: I called the first function minmax rather than minMax because of similarity with the standard min and max functions. The clipped version deviates enough to fall back to my normal naming conventions.

Happy coding...

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