When you’re designing blocks, it’s a good strategy to make them as reusable as possible. Don’t over-optimize a block for that one particular actor. Say, for instance, you need to make a slime that turns blue for 5 seconds when the player hits it. If the “blue” and “5 seconds” are hard-coded into the block’s code, what happens when you need a slime that turns red for 4 seconds instead?

That’s what properties are for.

This block, for example, could declare two properties: the color to use, and the duration, and then implement its logic in terms of these properties:

  export const PROPS = [
    propColor("Color"),
    propNumber("Duration", 3)
  ];

  export function onInit() {
    // Start green.
    setTint(0, 1, 0);
  }

  export function onCollision() {
    // Bump! Change to the requested color.
    setTintColor(props.Color);
    // Remind ourselves to change back to green.
    sendToSelfDelayed(props.Duration, "RestoreColor");
  }

  export function onRestoreColor() {
    setTint(0, 1, 0);
  }
  

Users of the block (you!) will now be able to assign its properties:

The more flexible you make your blocks, the more you will be able to reuse them in different actors and contexts!