Merge pull request dlang-tour#348 from Imperatorn/patch-1

Interfaces are implemented

basics/interfaces.md

@@ -4,7 +4,7 @@ D allows defining `interface`s which are technically like
 `class` types, but whose member functions must be implemented
 by any class inheriting from the `interface`.
 
-    interface Animal {
+    interface IAnimal {
         void makeNoise();
     }
 
@@ -13,14 +13,13 @@ by `Dog` because it inherits from the `Animal` interface.
 Essentially `makeNoise` behaves like an `abstract` member
 function in a base class.
 
-    class Dog : Animal {
-        override void makeNoise() {
+    class Dog : IAnimal {
+        void makeNoise() {
             ...
         }
     }
 
-    auto dog = new Dog;
-    Animal animal = dog; // implicit cast to interface
+    IAnimal animal = new Dog(); // implicit cast to interface
     animal.makeNoise();
 
 Although a class may only directly inherit from *one* base class,
@@ -36,7 +35,7 @@ allowing `final` (i.e. non-overridable) functions in an `interface`.
 This enforces specific behaviours customized by overriding
 other abstract `interface` functions.
 
-    interface Animal {
+    interface IAnimal {
         void makeNoise();
         final doubleNoise() // NVI pattern
         {
@@ -55,11 +54,7 @@ other abstract `interface` functions.
 ```d
 import std.stdio : writeln;
 
-interface Animal {
-    /*
-    Virtual function
-    which must be overridden!
-    */
+interface IAnimal {
     void makeNoise();
 
     /*
@@ -77,22 +72,22 @@ interface Animal {
     }
 }
 
-class Dog: Animal {
-    override void makeNoise() {
+class Dog: IAnimal {
+    void makeNoise() {
         writeln("Woof!");
     }
 }
 
-class Cat: Animal {
-    override void makeNoise() {
+class Cat: IAnimal {
+    void makeNoise() {
         writeln("Meeoauw!");
     }
 }
 
 void main() {
-    Animal dog = new Dog;
-    Animal cat = new Cat;
-    Animal[] animals = [dog, cat];
+    IAnimal dog = new Dog;
+    IAnimal cat = new Cat;
+    IAnimal[] animals = [dog, cat];
     foreach(animal; animals) {
         animal.multipleNoise(5);
     }