Type checks and casts

While writing your code, you may often be inclined to check what type your object is using, is, and cast it using as. As an example, let's imagine we're building a system for superheroes. Each superhero has their own set of methods:

interface Superhero 
class Batman : Superhero { 
    fun callRobin() { 
        println("To the Bat-pole, Robin!") 
    } 
} 
 
class Superman : Superhero { 
    fun fly() { 
        println("Up, up and away!") 
    } 
} 

There's also a function where a superhero tries to invoke their superpower:

fun doCoolStuff(s: Superhero) { 
    if (s is Superman) { 
        (s as Superman).fly() 
    } 
    else if (s is Batman) { 
  ...