observerutil 0.1.3

Let you implement observer pattern from the box

observerutil is simple and powerful observer pattern tool.

How to install

You could install from PyPi:

$ python3 -m pip install observerutil

Any callable can become observer

from typing import Any
from observerutil import Observers

def func_a(message: Any):
    ...

def func_b(message: Any):
    ...

observers = Observers([func_a])
observers.add(func_b)
my_message = 'some message here'
# or
my_message = {1: 2}

# Distribute message to func_a and func_b.
# Any exceptions will be ignored.
observers.send_message(my_message)

But in this case any exception will be ignored. If you would like to catch exceptions then use Observer with error handler.

from typing import Any
from observerutil import Observer, Observers, ErrorHandler


def func_a(message: int):
    print(100 / message)


def write_exception_to_logs(exc: Exception):
    ...


observer = Observer(func_a, error_handler=write_exception_to_logs)
observers = Observers()
observers.add(func_a)

my_message = 0
observers.send_message(my_message)

If you would like to adapt message for observers in the collection then add message adapter

from typing import Any
from observerutil import Observers


def func_a(message: int):
    print(100 / message)

def convert_to_int(message: str):
    # exception of adapter is not excepted by Observers instance.
    # add try...except by self if required.
    try:
        return int(message)
    except Exception:
        return None

observers = Observers(message_adapter=convert_to_int)
observers.add(func_a)

my_message = '2'
# any exceptions of observers (funcs or Observer instances) will be excepted while sending
observers.send_message(my_message)