Step 6: Openable Things

What This Version Does

The feed dispenser at the petting zoo and a lunchbox on the main path can now be opened and closed. You must open them before you can see or access what's inside.

What's New (Compared to V5)

V5 introduced containers you could freely put things in. V6 adds a closed state — containers that must be opened first.

What You'll Learn

OpenableTrait

OpenableTrait gives an entity an open/closed state. The player can use the built-in open and close actions to change it.

lunchbox.add(new OpenableTrait({
  isOpen: false,          // Starts closed
  canClose: true,         // Player can close it again
  revealsContents: true,  // Opening shows what's inside
}));

By itself, OpenableTrait just tracks whether something is open or closed. Its power comes from combining it with other traits.

OpenableTrait + ContainerTrait

When an entity has BOTH OpenableTrait and ContainerTrait:

• Closed container: contents are hidden. look in lunchbox says it's closed. put map in lunchbox is blocked.
• Open container: contents are visible. All container operations work normally.

This is how you create discoverable containers — the player opens something and finds items inside.

Key Properties

Placing Items in Closed Containers

During world setup, you might need to place items inside a container that starts closed. The engine normally blocks put X in Y when Y is closed. The workaround is to temporarily open the container:

lunchbox.get(OpenableTrait)!.isOpen = true;   // Temporarily open
world.moveEntity(juice.id, lunchbox.id);       // Place item inside
lunchbox.get(OpenableTrait)!.isOpen = false;   // Close it back

Future Combinations

OpenableTrait becomes even more powerful in V7 when combined with LockableTrait — creating locked containers and doors that must be unlocked before they can be opened.

Commands to Try

> south                     Go to Main Path
> examine lunchbox          It's closed
> open lunchbox             Open it — "Inside you can see a juice box"
> take juice                Take the juice box
> close lunchbox            Close it again
> east                      Go to Petting Zoo
> open dispenser            Open the feed dispenser
> take dispenser            Can't — it's scenery

The Code

See src/v06.ts for the complete, commented source.

Key Takeaway

OpenableTrait adds open/close state. Combined with ContainerTrait, it creates containers that hide their contents until opened. The open and close actions are built into stdlib.