Swift can lazy and didSet set together

Question

I have a property

public lazy var points: [(CGFloat,CGFloat,CGFloat)] = {         var pointsT = [(CGFloat,CGFloat,CGFloat)]()         let height = 100.0         for _ in 1...10 {             pointsT.append((someValue,someValue,100.0))         }         return pointsT     }() 

And i want to add a didSet method, is it possible?

Answer 1

Short answer: no.

Try out this simple example in some class or method of yours:

lazy var myLazyVar: Int = {     return 1 } () {     willSet {         print("About to set lazy var!")     } } 

This gives you the following compile time error:

Lazy properties may not have observers.

---

With regard to the let statement in the other answer: lazy variable are not necessary just "let constants with delayed initialisation". Consider the following example:

struct MyStruct {     var myInt = 1      mutating func increaseMyInt() {         myInt += 1     }      lazy var myLazyVar: Int = {         return self.myInt     } () }  var a = MyStruct() print(a.myLazyVar) // 1 a.increaseMyInt() print(a.myLazyVar) // 1: "initialiser" only called once, OK a.myLazyVar += 1 print(a.myLazyVar) // 2: however we can still mutate the value                    //    directly if we so wishes