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:

<!-- 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:

# 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:

# 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:

# 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

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

# 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

# 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

# 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:

📂 Phase 1: Discovery
   Found: 36 rooms, 54 objects, 6 characters
   Found: 2 containers  # NEW!

Containers suppress the "missing type declaration" warning:

# 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! 🎉