container

# Container > **Intermediate scopes that provide inheritance without being navigable rooms.** Containers are directories that define shared properties for their children, without themselves being places you can "go to." ## The OpenLaszlo Inspiration In OpenLaszlo (Don Hopkins' earlier work!), `<node>` was a fundamental building block: ```xml <!-- OpenLaszlo: <node> provides inheritance without visual layout --> <node name="mazeDefaults"> <attribute name="isDark" value="true"/> <attribute name="hasDanger" value="true"/> </node> <view extends="mazeDefaults"> <!-- Inherits isDark, hasDanger --> </view> ``` MOOLLM's `CONTAINER.yml` does the same for adventure directories: ```yaml # maze/CONTAINER.yml container: name: "The Twisty Maze" inherits: is_dark: true is_dangerous: true grue_rules: can_appear: true ``` All rooms inside `maze/` automatically inherit these properties! --- ## Container vs Room vs Meta | Type | File | Navigable? | Inherits to children? | |------|------|------------|----------------------| | Room | `ROOM.yml` | ✅ Yes | ❌ No | | Container | `CONTAINER.yml` | ❌ No | ✅ Yes | | Meta | `.meta.yml` | ❌ No | ❌ No (just metadata) | **Use Container when:** - You want to define shared properties - Children should inherit automatically - The directory itself is not a place **Use Room when:** - The directory is a navigable location - It has exits and can be entered **Use .meta.yml when:** - Just declaring "this is a system directory" - No inheritance needed --- ## Inheritance Rules ### Cascade Down Properties in `inherits:` flow to ALL descendants: ``` maze/ ├── CONTAINER.yml # inherits: { is_dark: true } ├── room-a/ │ └── ROOM.yml # Inherits is_dark: true ├── room-b/ │ └── ROOM.yml # Inherits is_dark: true └── deep/ └── CONTAINER.yml # Can add MORE inherits └── room-c/ └── ROOM.yml # Inherits from BOTH containers! ``` ### Override by Redefining Children can override inherited values: ```yaml # maze/room-f/ROOM.yml room: name: "The Treasure Chamber" is_dark: false # Override! This room has magical light ``` ### Merge, Don't Replace For objects and arrays, inheritance MERGES: ```yaml # maze/CONTAINER.yml container: inherits: rules: - "Grues patrol in darkness" # maze/room-g/ROOM.yml room: rules: - "This room has a pit trap" # ADDS to inherited rules ``` Result: room-g has BOTH rules. --- ## Defaults vs Inherits | Field | Purpose | |-------|---------| | `inherits` | Properties that children GET automatically | | `defaults` | Values to use IF a child doesn't define them | ```yaml container: # Every child room IS dark (forced) inherits: is_dark: true # If a room doesn't define atmosphere, use this defaults: room: atmosphere: "damp and musty" ``` --- ## Use Cases ### Maze with Grue Rules ```yaml # maze/CONTAINER.yml container: name: "The Twisty Maze" description: "Passages all alike... or are they?" inherits: is_dark: true is_dangerous: true grue_rules: can_appear: true safe_with_light: true rules: - "No teleportation" - "Breadcrumbs disappear after 3 turns" - "Echoes alert nearby rooms" ambient: sound: "dripping water" smell: "wet stone" temperature: cold ``` ### Animal Character Category ```yaml # characters/animals/CONTAINER.yml container: name: "Animal Characters" description: "Non-human beings with souls" inherits: type: animal has_instincts: true defaults: character: can_speak_human: false pet_able: true diet: omnivore ``` ### Kitchen Appliances ```yaml # kitchen/appliances/CONTAINER.yml container: name: "Kitchen Appliances" inherits: type: appliance requires_power: true defaults: object: breakable: true fixable_with: "wrench" ``` --- ## Resolution Order When looking up a property: 1. **Self** — Check the object/room itself 2. **Parent Container** — Check `CONTAINER.yml` in parent dir 3. **Grandparent Container** — Keep going up 4. **Adventure Defaults** — `ADVENTURE.yml` defaults 5. **Prototype** — The skill template ``` maze/deep/room-c/ROOM.yml ↓ inherits from maze/deep/CONTAINER.yml ↓ inherits from maze/CONTAINER.yml ↓ inherits from ADVENTURE.yml (if it has defaults) ↓ inherits from skills/room/ROOM.yml.tmpl ``` --- ## Linter Behavior The linter recognizes `CONTAINER.yml`: ```bash 📂 Phase 1: Discovery Found: 36 rooms, 54 objects, 6 characters Found: 2 containers # NEW! ``` Containers suppress the "missing type declaration" warning: ```yaml # Before: maze/ triggers warning ⚠️ Directory has room children but no ROOM.yml # After: maze/CONTAINER.yml exists ✅ maze/ is a container (not a room) ``` --- ## Related Patterns - **Prototype Inheritance** (Self/JavaScript) — Objects inherit from prototypes - **Lexical Scope** (Lisp/JavaScript) — Inner scopes access outer variables - **Cascading** (CSS) — Styles flow from parent to child - **XML Namespaces** — Context flows through the tree --- ## Credits - **OpenLaszlo** — The `<node>` element as non-visual scope - **Self** — Prototype inheritance without classes - **CSS** — The cascade as inheritance mechanism - **Don Hopkins** — For remembering OpenLaszlo! 🎉