python events

lib_event.py

events = {}

def register_event(event: str, fn: callable):
    if not event in events:
        events[event] = []
    events[event].append(fn)
    
        
def dispatch(event: str, *args, **kwargs):
    if not event in events:
        raise ValueError("event %s is not registered!" % event)
    handlers = events[event]
    for fn in handlers:
        fn(*args, **kwargs)
        

main.py

import functools
from lib_event import register_event, dispatch

users = {}

def send_email(user):
    print("email has been sent to %s" % user["email"])

def notify(msg, user):
    print("%s: %s" % (msg, user))

def create_user(name):
    if name in users:
        print("user %s already created!" % name)
        return
    user = {"name": name, "email": name + "@python.org", "password": "123"}
    users[name] = user
    dispatch("user_created", user)

def change_password(name, password):
    if name not in users:
        print("user %s not found!" % name)
        return
    user = users[name]
    user["password"] = password
    dispatch("password_changed", user)

def main():
    print("> create user")
    create_user("irul")
    print("> create user")
    create_user("jaka")
    print("> create user")
    create_user("irul")

    print("> change password")
    change_password("jaka", "456")
    
    print("> all users")
    for name in users:
        print(users[name])
        
if __name__ == '__main__':
    register_event("user_created", functools.partial(notify, "user successfuly created"))
    register_event("user_created", send_email)
    register_event("password_changed", functools.partial(notify, "password successfuly changed"))
    register_event("password_changed", send_email)
    
    main()

Result:

> create user
user successfuly created: {'name': 'irul', 'email': 'irul@python.org', 'password': '123'}
email has been sent to irul@python.org
> create user
user successfuly created: {'name': 'jaka', 'email': 'jaka@python.org', 'password': '123'}
email has been sent to jaka@python.org
> create user
user irul already created!
> change password
password successfuly changed: {'name': 'jaka', 'email': 'jaka@python.org', 'password': '456'}
email has been sent to jaka@python.org
> all users
{'name': 'irul', 'email': 'irul@python.org', 'password': '123'}
{'name': 'jaka', 'email': 'jaka@python.org', 'password': '456'}


** Process exited - Return Code: 0 **
Press Enter to exit terminal