Hands-On Design Patterns with Kotlin

Saving memory

What's the problem wehave with our snails? They're actually quite fat, heavyweight snails.

We would like to put them on a diet. Each snail stores eight images within its snaily body. But actually, those images are the same for each snail.

What if we extract those sprites:

val sprites = List(8) { i ->    java.io.File(when {        i == 0 -> "snail-left.jpg"        i == 1 -> "snail-right.jpg"        i in 2..4 -> "snail-move-left-${i-1}.jpg"        else -> "snail-move-right${(4-i)}.jpg"    })}

Then we pass this list each time to the getCurrentSprite() function:

fun TansanianSnail.getCurrentSprite(sprites: List<java.io.File>) :     java.io.File { ... }

That way, we'll only consume 256 KB of memory, no matter how many snails we generate. We could generate millions of ...