eventure 0.4.3

A Python library providing a robust, type-safe event system for game development and simulation.

Eventure

A powerful event-driven framework for simulations, games, and complex systems with comprehensive event sourcing, querying, and analysis capabilities.

Features

• Event Management

  • Immutable events with tick, timestamp, type, data, and unique ID attributes
  • Parent-child relationships between events for cascade tracking
  • JSON serialization for persistence and network transmission

• Event Log & Bus

  • EventLog: Track, save, and replay sequences of events
  • EventBus: Decouple event producers from consumers with wildcard subscriptions
  • Game state reconstruction through deterministic event replay

• Advanced Event Querying

  • Filter events by type, data content, or relationships
  • Analyze event cascades and parent-child structures
  • Count, group, and visualize events with detailed formatting
  • Query events by tick, root events, and other criteria

• Ready-to-Use Examples

  • Cryptocurrency Trading Bot: Financial simulation with market events
  • Adventure Game: Complete game state management through events

• Developer-Friendly

  • Type-safe API with comprehensive type hints
  • Zero dependencies (pure Python implementation)
  • Extensive test coverage
  • Detailed documentation

Core Concepts

Event Sourcing Architecture

Eventure is built on the event sourcing architectural pattern, which means:

1. Events as the Source of Truth

   • All state changes are represented as immutable events
   • The sequence of events becomes the authoritative record
   • Current state is derived by replaying the event history

2. Implementation in Eventure

   • EventLog: Serves as the event store, maintaining the complete event history
   • Event objects: Immutable records with type, data, tick, and relationship information
   • State derivation: Game or application state is reconstructed by replaying events
   • EventQuery: Provides powerful tools to analyze and understand the event history

3. Benefits in Practice

   • Complete audit trail for debugging and analysis
   • Time-travel capabilities through historical state reconstruction
   • Natural support for undo/redo and save/load features
   • Perfect reproducibility of any system state

# Example: State reconstruction from events
events = log.get_events_until_tick(5)
state_at_tick_5 = derive_game_state(events)

# Restore game to a previous state
historical_state = derive_game_state(events_until_save_point)

Tick-Based System

Eventure uses a tick-based system that provides several key advantages:

1. Deterministic Execution

   • Events within a tick are processed in a consistent, predictable order
   • Eliminates race conditions and timing-related bugs
   • Makes debugging significantly easier with reproducible scenarios

2. Discrete Time Steps

   • Game time advances in well-defined increments
   • Each tick represents a clear, isolated state transition
   • Multiple events can be processed within a single tick

3. Performance Optimization

   • Events can be batched and processed efficiently within ticks
   • Reduced overhead compared to continuous time systems

4. Flexible Simulation Control

   • Easily implement pause, step-forward, or fast-forward functionality
   • Run simulations at different speeds without affecting logic
   • Perfect for debugging complex scenarios or analyzing specific moments

# Example: Using ticks for deterministic ordering
log.add_event("market.price_update", {"price": 100})  # Tick 1
log.advance_tick()
log.add_event("trading.buy_order", {"amount": 10})    # Tick 2

Event Cascade System

Eventure's event cascade system tracks relationships between events, providing several powerful capabilities:

1. Causal Tracking

   • Every event can have a parent event that triggered it
   • Complete traceability from cause to effect
   • Understand complex chains of interactions

2. Debugging and Analysis

   • Trace the root cause of any system behavior
   • Visualize complete event cascades
   • Identify unexpected side effects or event chains

3. Rich Query Capabilities

   • Filter events by their relationships
   • Find all events triggered by a specific root event
   • Analyze patterns in event propagation

4. System Understanding

   • Map complex interactions between system components
   • Document emergent behaviors
   • Improve system design through relationship analysis

# Creating related events
def on_enemy_defeated(event):
    # These events will be linked to the parent event
    bus.publish("treasure.drop", {"item": "gold_coins"}, parent_event=event)
    bus.publish("experience.gain", {"amount": 100}, parent_event=event)

# Querying related events
root_event = query.get_event_by_id("evt_123")
cascade_events = query.get_cascade_events(root_event)

Installation

# Using pip
pip install eventure

# Using uv (recommended)
uv add eventure

Core Components

Event

The fundamental unit representing something that happened:

from eventure import Event

# Create an event
event = Event(
    tick=0, 
    timestamp=time.time(), 
    type="user.login", 
    data={"user_id": 123, "ip": "192.168.1.1"}
)

# Events have unique IDs and can be serialized
print(f"Event ID: {event.id}")  # Format: {tick}-{typeHash}-{sequence}
json_str = event.to_json()

EventLog

Tracks, stores, and manages events in a time-ordered sequence:

from eventure import EventLog

# Create an event log
log = EventLog()

# Add events to the log
event = log.add_event("user.login", {"user_id": 123})
log.advance_tick()  # Move to next discrete time step
log.add_event("user.action", {"user_id": 123, "action": "view_profile"})

# Create child events (establishing causal relationships)
parent = log.add_event("combat.start", {"player": "hero", "enemy": "dragon"})
child = log.add_event("combat.attack", {"damage": 15}, parent_event=parent)

# Save and load event history
log.save_to_file("game_events.json")
new_log = EventLog.load_from_file("game_events.json")

EventBus

Manages event publication and subscription:

from eventure import EventBus

# Create an event bus connected to a log
bus = EventBus(log)

# Subscribe to specific events
def on_login(event):
    print(f"User {event.data['user_id']} logged in")
    
unsubscribe = bus.subscribe("user.login", on_login)

# Subscribe with wildcards
bus.subscribe("user.*", lambda e: print(f"User event: {e.type}"))
bus.subscribe("*.error", lambda e: print(f"Error: {e.data['message']}"))
bus.subscribe("*", lambda e: print(f"Any event: {e.type}"))

# Publish events
bus.publish("user.login", {"user_id": 456})

# Unsubscribe when done
unsubscribe()

Wildcard Event Subscriptions

Eventure supports three powerful wildcard subscription patterns that allow handlers to receive multiple types of events:

# Exact match subscription
bus.subscribe("player.move", on_player_move)

# Prefix wildcard - receives all events with a specific prefix
bus.subscribe("player.*", on_any_player_event)  # player.move, player.attack, etc.

# Suffix wildcard - receives all events with a specific suffix
bus.subscribe("*.error", on_any_error_event)  # network.error, auth.error, etc.

# Global wildcard - receives ALL events
bus.subscribe("*", on_any_event)

When multiple handlers match an event, they are called in order of specificity:

1. Exact match handlers
2. Prefix wildcard handlers
3. Suffix wildcard handlers
4. Global wildcard handlers

This hierarchical dispatch system allows for both specific and general event handling, making it easy to implement logging, debugging, or cross-cutting concerns.

EventQuery

Powerful API for querying, analyzing, and visualizing events:

from eventure import EventQuery

# Create a query interface for an event log
query = EventQuery(log)

# Filter events
combat_events = query.get_events_by_type("combat.attack")
dragon_events = query.get_events_by_data("enemy", "dragon")

# Analyze relationships
child_events = query.get_child_events(parent_event)
cascade = query.get_cascade_events(root_event)

# Count and group
type_counts = query.count_events_by_type()
print(f"Combat events: {type_counts.get('combat.attack', 0)}")

# Get events by tick or relationship
tick5_events = query.get_events_at_tick(5)
root_events = query.get_root_events()

# Visualize events and cascades
query.print_event_cascade()  # All events organized by tick
query.print_single_cascade(root_event)  # Show a specific cascade
query.print_event_details(event)  # Show details of a single event

Example Applications

Eventure includes two complete example applications demonstrating real-world usage:

Cryptocurrency Trading Bot

A simulated trading system showing market events, trading signals, and order execution:

from examples.crypto_trading_bot import CryptoTradingBot

# Create and run a trading simulation
bot = CryptoTradingBot()
bot.run_simulation()

# Query interesting patterns from the event log
query = EventQuery(bot.event_log)
buy_signals = query.get_events_by_data("signal", "BUY")

Key features demonstrated:

• Market simulation with price and volume updates
• Trading strategy implementation via events
• Order creation and execution
• Portfolio tracking
• Event-based system analysis

Adventure Game

A text-based adventure game showing game state management:

from examples.adventure_game import AdventureGame

# Create and run a game
game = AdventureGame()
game.run_game()

# Analyze game events
query = EventQuery(game.event_log)
combat_events = query.get_events_by_type("combat.start")
treasure_events = query.get_events_by_type("treasure.found")

Key features demonstrated:

• Room navigation and discovery
• Item collection and inventory management
• Enemy encounters and combat
• Event cascades (e.g., entering a room triggers discoveries)
• Game state derivation from events

EventQuery API in Detail

The EventQuery API provides a consistent set of methods for analyzing and visualizing events:

Filtering Events

# By event type
strategy_signals = query.get_events_by_type("strategy.signal")

# By data content
buy_signals = query.get_events_by_data("signal", "BUY")
dragon_encounters = query.get_events_by_data("enemy", "dragon")

# By tick
tick_3_events = query.get_events_at_tick(3)

# Root events (with no parent or parent in previous tick)
root_events = query.get_root_events()

Relationship Queries

# Direct children of an event
children = query.get_child_events(parent_event)

# Complete cascade (parent, children, grandchildren, etc.)
full_cascade = query.get_cascade_events(root_event)

Analysis Methods

# Count events by type
counts = query.count_events_by_type()
print(f"Total combat events: {sum(counts.get(t, 0) for t in counts if t.startswith('combat.'))}")

Visualization

# Print all events organized by tick
query.print_event_cascade()

# Print a specific event cascade
query.print_single_cascade(root_event)

# Print details of a specific event
query.print_event_details(event)

Event Visualization Examples

The EventQuery API provides powerful visualization capabilities for event cascades. Here are some examples from the included Adventure Game example:

Room Entry and Combat Sequence

┌─── TICK 4 ───┐
│
  ↓ room.enter (caused by: player.move @ tick 3)
    ID: 4-FADA-1
    Data:
      room: treasury
      description: Glittering treasures fill this heavily guarded room.
    │
    └─ enemy.encounter
    │ ID: 4-ADCF-1
    │ Data:
    │   enemy: dragon
    │   message: A dragon appears before you!
└───────────────┘

┌─── TICK 5 ───┐
│
  ↓ combat.start (caused by: enemy.encounter @ tick 4)
    ID: 5-ABAA-1
    Data:
      enemy: dragon
      enemy_health: 100
      message: Combat with dragon begins!
│
  ↓ combat.round (caused by: enemy.encounter @ tick 4)
    ID: 5-BDBB-1
    Data:
      enemy: dragon
      round: 1
      message: Round 1 against dragon!
    │
    └─ combat.damage_dealt
    │ ID: 5-DDDF-1
    │ Data:
    │   enemy: dragon
    │   amount: 18
    │   message: You hit the dragon for 18 damage!
└───────────────┘

This visualization shows:

• Events organized by tick
• Parent-child relationships with indentation
• Causal connections between events (shown with arrows)
• Complete event data for analysis

To generate these visualizations in your code:

# Print all events in the log organized by tick
query.print_event_cascade()

# Print a specific cascade starting from a root event
query.print_single_cascade(root_event)

# Print details of a single event
query.print_event_details(event)

Advanced Usage

Event Replay and State Reconstruction

One of Eventure's most powerful features is the ability to reconstruct state by replaying events:

# State can be derived entirely from events
def derive_game_state(events):
    state = {"health": 100, "inventory": [], "location": "start"}
    
    for event in events:
        if event.type == "player.damage":
            state["health"] -= event.data["amount"]
        elif event.type == "item.pickup":
            state["inventory"].append(event.data["item"])
        elif event.type == "player.move":
            state["location"] = event.data["destination"]
            
    return state

# Current state from all events
current_state = derive_game_state(log.events)

# Historical state (state at tick 5)
tick_5_events = [e for e in log.events if e.tick <= 5]
historical_state = derive_game_state(tick_5_events)

Event Cascading with Parent References

# Create a handler that triggers follow-up events
def combat_handler(event):
    if event.data.get("enemy_health", 0) <= 0:
        # Generate a cascade event based on the original event
        bus.publish("enemy.defeated", 
                   {"enemy": event.data["enemy"]},
                   parent_event=event)  # Parent reference maintains event chain

# Subscribe to combat events
bus.subscribe("combat.attack", combat_handler)

API Reference

For the complete API documentation, see the API Reference.

Development

Setup Development Environment

# Clone the repository
git clone https://github.com/yourusername/eventure.git
cd eventure

# Install development dependencies
uv sync --all-extras

Running Tests

# Run all tests
just test

License

MIT License