Hands-On Design Patterns with Swift

Generic functions

Let's consider the following code, which isn't implemented with generics:

func compareInts(_ a: Int, _ b: Int) -> Int {    if a > b { return 1 }    if a < b { return -1 }    return 0}

This works with integers, but how would it work with Double? We'd need to implement another method:

func compareDoubles(_ a: Double, _ b: Double) -> Int {    if a > b { return 1 }    if a < b { return -1 }    return 0}

Generics-based programming aims to resolve this issue. In Swift, we have the Comparable protocol, which we can use in order to implement a generic compare function:

func compare<T>(_ a: T, _ b: T) -> Int where T: Comparable {    if a > b { return 1 }    if a < b { return -1 }    return 0}

Let's break it down:

• <T> indicates that this function is generic, ...