The name
property is marked as protected
. This was added in TypeScript 1.3 and is now firmly established.
The makeSound
method is marked as abstract
, as is the class. You cannot directly instantiate an Animal
now, because it is abstract. This is part of TypeScript 1.6, which is now officially live.
abstract class Animal {
constructor(protected name: string) { }
abstract makeSound(input : string) : string;
move(meters) {
alert(this.name + " moved " + meters + "m.");
}
}
class Snake extends Animal {
constructor(name: string) { super(name); }
makeSound(input : string) : string {
return "sssss"+input;
}
move() {
alert("Slithering...");
super.move(5);
}
}
The old way of mimicking an abstract method was to throw an error if anyone used it. You shouldn’t need to do this any more once TypeScript 1.6 lands in your project:
class Animal {
constructor(public name) { }
makeSound(input : string) : string {
throw new Error('This method is abstract');
}
move(meters) {
alert(this.name + " moved " + meters + "m.");
}
}
class Snake extends Animal {
constructor(name) { super(name); }
makeSound(input : string) : string {
return "sssss"+input;
}
move() {
alert("Slithering...");
super.move(5);
}
}