Data update

Task/Abstract-type/Swift/abstract-type.swift

@@ -0,0 +1,33 @@
+protocol Pet {
+	var name: String { get set }
+	var favouriteToy: String { get set }
+
+	func feed() -> Bool
+
+	func stroke() -> Void
+
+}
+
+extension Pet {
+    // Default implementation must be in an extension, not in the declaration above
+
+    func stroke() {
+		print("default purr")
+	}
+}
+
+struct Dog: Pet {
+	var name: String
+	var favouriteToy: String
+	
+	// Required implementation
+	func feed() -> Bool {
+		print("more please")
+		return false
+	}
+	// If this were not implemented, the default from the extension above
+	// would be called.
+	func stroke() {
+		print("roll over")
+	}
+}