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iOS Object-Oriented Swift Inheritance Inheritance and Initializers

Giuseppe Santaniello
PLUS
Giuseppe Santaniello
Courses Plus Student 1,800 Points
Posted by Giuseppe Santaniello
Giuseppe Santaniello
Courses Plus Student 1,800 Points

optional parameter and hash symbol in a function

Hi, Amit in your example when you override the discounted Price function, you have inserted an underscore as optional parameter, but suppose that the function in the SuperClass has this signature:

func discountedPrice (#percentage: Double) -> Double{
    return price - (price * percentage / 100)
}

I don't need to insert the underscore as optional parameter, it's correct ?

In SubClass:

override func discountedPrice (percentage: Double = 10.0) -> Double{
   return super.discountedPrice(percentage: percentage)
}

Thanks, and sorry for my English ;)

2 Answers

mattlebl
mattlebl
10,849 Points
mattlebl
mattlebl
10,849 Points

Hi! I'm not Amit, but I hope I can help you anyway. I'm not sure why you assume he puts a hash symbol in the superclass initializer.

Product class initializer

func discountedPrice(percentage: Double) -> Double {
  return price - (price * percentage / 100)
}

There is no underscore before the percentage parameter, as it is nonoptional. A percentage must be specified.

Clothing class initializer

override func discountedPrice(_ percentage: Double = 10.0) -> Double {
    return super.discountedPrice(percentage) // Dry code FTW!
}

There is an underscore this time because a default value was specified. Amit explained: there is a narrow profit margin for clothing, so discounts are generally only 10%. Therefore, a good default value would be 10.0. If a percentage isn't specified, 10.0 will be used. If a percentage is specified, then that one will be used.

Hope I helped!

mattlebl
mattlebl
10,849 Points

No problem. Good luck with your learning!