polymorphism completed

typescript/Polymorphism.md

@@ -0,0 +1,5 @@
+# Polymorphism
+
+Relevant files
+
+- [index.ts](./inheritance/index.ts)

typescript/inheritance/README.md

@@ -2,7 +2,6 @@
 
 Relevant files:
 
-- [index.ts](./index.ts)
 - [animal.ts](./animal.ts)
 - [cat.ts](./cat.ts)
 - [dog.ts](./dog.ts)

typescript/inheritance/index.ts

@@ -1,8 +1,14 @@
 import { Dog } from "./dog";
 import { Cat } from "./cat";
+import { Animal } from "./animal";
 
-const d = new Dog('buster');
-const c = new Cat('mittens');
+// because cat and dog are subclasses of animal, they can be stored in an array of animals
+const animals: Animal[] = [
+  new Dog('buster'),
+  new Cat('mittens')
+]
 
-d.make_sound();
-c.make_sound();
+for (const a of animals) {
+  // when calling the make_sound function, the implementation of the actual class gets called (in this case cat or dog)
+  a.make_sound();
+}