Sample demo of global computed variable and global willSet, didSet methods

global_variable_demo.swift

import Foundation

var a: Double = 3
var aSquared: Double {
    get {
        return pow(a, 2)
    }
    set {
        a = sqrt(newValue)
    }
}
a = 5
print(aSquared)

a = 6
print(aSquared)

aSquared = 4
print(aSquared)
print(a)


var greeting: String = "Hello" {
    willSet(newValue) {
        print("\(greeting), \(newValue)")
    }
    didSet {
        print("\(oldValue), \(greeting)")
    }
}

greeting = "Bye"