Python CommandBus

A simple commandBus for python3.

Usage

Configure

Set up the command bus with all the command handlers. The HandlerMiddleware maps the class name of a Command to the handler that handles it.

# file: setup.py

from command_bus import CommandBus, CommandHandler, HandlerMiddleware

class CarHandler(CommandHandler):
    def handle(self, car):
        # process the Car
        
class BikeHandler(CommandHandler):
    def handle(self, bike):
        # process the bike

command_bus = CommandBus([
    HandlerMiddleware({
        'Car': CarHandler(),
        'Bike': BikeHandler(),
    })
])

Execute

To execute a Command, instantiate one and give it to the CommandBus to process it.

from setup import command_bus

class Bike():
    def __init__(self, gears):
        self.gears = gears
        
command_bus.handle(Bike(21)) # BikeHandler is executed using Bike 

Middleware

You can easily add extra functionalities that needs to be executed on some or all of the commands passed. Just create some Middleware and add it to the CommandBus

from command_bus import CommandBus, CommandHandler, HandlerMiddleware

class LoggingMiddleware(Middleware):
    def execute(self, command, next):
        print(command.__class__.__name__)
        return next(command)
        
command_bus = CommandBus([
    LoggingMiddleware(),
    HandlerMiddleware({})
])