Skip to main content

Updatable

The Updatable interface defines the contract for objects that require per-frame updates. It is the base interface for System and can be implemented by any class that needs to participate in the game loop.

Overview​

class Updatable {
public:
    virtual ~Updatable() = default;
    virtual void update(UpdateContext& updateContext) noexcept = 0;
};

The interface is intentionally minimal:

  • Single pure virtual method update()
  • noexcept guarantee for exception safety in the game loop
  • Virtual destructor for proper cleanup

Usage​

Implementing Updatable​

class PhysicsSystem : public System {  // System inherits from Updatable
public:
    void update(UpdateContext& ctx) noexcept override {
        // Called every frame
        float dt = ctx.deltaTime;
        // Process physics...
    }
};

UpdateContext​

The update() method receives an UpdateContext with frame information:

struct UpdateContext {
    float deltaTime;           // Time since last frame (seconds)
    CommandBuffer* commands;   // For deferred operations
    GameWorld* gameWorld;      // Reference to the world
};

Design Rationale​

noexcept Requirement​

The update() method is marked noexcept because:

  1. Game loop stability - Exceptions during update can crash the game
  2. Performance - noexcept enables compiler optimizations
  3. Predictability - Forces error handling at the source
void update(UpdateContext& ctx) noexcept override {
    // Must handle all errors internally
    if (auto result = riskyOperation(); !result) {
        LOG_ERROR("Operation failed");
        return;  // Don't throw
    }
}

Interface Segregation​

Updatable is separate from System to allow:

  • Non-system objects to be updatable
  • Systems that don't need updates (rare)
  • Composition over inheritance patterns

Relationship with System​

System extends Updatable and adds:

  • GameWorld* member for world access
  • init() callback for initialization
class System : public Updatable {
protected:
    GameWorld* gameWorld_ = nullptr;
    
public:
    virtual void init(GameWorld& gameWorld) noexcept;
    void update(UpdateContext& ctx) noexcept override = 0;
};

See Also​