pyeventhub

Event Handling Framework with EventEmitter

This Python module implements an event handling framework (EventEmitter) that supports prioritization (PriorityEvent), event filtering, and processing using threading, queues (queue module), heap operations (heapq module), and logging (logging module) capabilities.

Classes

EventHandler

Defines an interface for handling events.

NotificationHandler

Extends EventHandler and handles notifications with specific ID and Message attributes.

Notification

Represents a notification entity with attributes ID, Message, and CreatedAt.

PriorityEvent

Represents an event with its associated priority for queueing and processing.

EventEmitter

Manages event registration, emission, and handling. Features include:

• Logging: Enables or disables logging and logs events with their priorities.
• Event Registration: Registers listeners and handlers for specific events.
• Event Emission: Emits events with context for cancellation and timeout.
• Event Processing: Processes events in priority order using heap operations.
• Event Handling: Dispatches events to registered handlers.

Example Usage

main.py

import threading
import time
import queue
import logging
from pyeventhub import EventEmitter, NotificationHandler, Notification

if __name__ == "__main__":
    logging.basicConfig(level=logging.INFO)

    # Example usage
    emitter = EventEmitter(logging=True)

    # Register notification handlers
    handler1 = NotificationHandler(name="EmailHandler")
    handler2 = NotificationHandler(name="SMSHandler")

    emitter.on_event("email_notification", handler1)
    emitter.on_event("sms_notification", handler2)

    # Registering listeners with filters
    def email_filter(data):
        if isinstance(data, Notification):
            return data.ID > 0  # Example filter: process only notifications with ID > 0
        return False

    chEmail = emitter.on("email_notification", email_filter)
    chSMS = emitter.on("sms_notification")

    # Simulate sending notifications with priority
    def send_notifications():
        emitter.emit_with_context(None, "email_notification", Notification(ID=1, Message="New email received", CreatedAt=time.time()), 2)  # Higher priority
        emitter.emit_with_context(None, "sms_notification", Notification(ID=2, Message="You have a new SMS", CreatedAt=time.time()), 1)  # Lower priority

    # Handle notifications asynchronously
    def handle_notifications():
        while True:
            if not chEmail.empty():
                notification = chEmail.get()
                print("Received email notification")
                handler1.handle(notification)
            if not chSMS.empty():
                notification = chSMS.get()
                print("Received SMS notification")
                handler2.handle(notification)

    send_thread = threading.Thread(target=send_notifications)
    handle_thread = threading.Thread(target=handle_notifications)

    send_thread.start()
    handle_thread.start()

    # Allow some time for notifications to be processed
    time.sleep(2)

    # Clean up
    emitter.close()