Learning Swift™ Programming

The Problem That Generics Solve

Let’s talk about the problem that generics solve. Consider this function, which swaps two integers:

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func swapTwoInts(inout a: Int, inout b: Int) {    let temporaryA = a    a = b    b = temporaryA}var a = 10var b = 1swapTwoInts(&a,&b)println(a) // 1println(b) // 10

This works just as expected. You are able to swap the two Ints by passing them as inout parameters to the function. The problem is that this function only works with Ints. If you try setting the variables to 10.5 (a double) or "Hello there" (a string), it will not work because 10.5 is a Double and "Hello there" is a String. This function only takes Ints. The function’s implementation itself (the code inside the function) ...