In the Going Further section of Checkpoint 8, Paul challenges us to use "a protocol extension to provide a default implementation for printSummary()". Paul suggests adding a string property requirement to the protocol (for type of building) and then adding the property and giving it a default value in the declaration of each of the structs. Ignoring the fact that this property should have been declared as static* so as not to waste space in each and every instance of Building, there is an even better solution.

Instead of adding a property for type everywhere, just have printSummary() use Self.self instead of the type property. The default printSummary() will now look like:

// This will print the name of the Type.
func printSummary() {
        print("Talk to \(agent) to buy this \(Self.self) for $\(cost).")
}

• In the case above where we used static, we get the name of the type by using Self.type.

  func printSummary() {
      print("Talk to \(agent) to buy this \(Self.type) for $\(cost).")
  }