Watchify

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About

watchify is an event-driven inter-object communication tool, promoting the segregation of complex functionalities into smaller ones while enabling their relationship through a third-party entity. This approach promotes loosely coupled implementations, simplifying Single Responsibility Principle commitment yet keeping a cohesive code. As a result, the code becomes more flexible, maintainable, testable, and overrall healthier.

Install

$ pip install watchify

Usage

from watchify import AbstractWatcher, Watchers
from watchify.logger import logger


class Food:
    def cook(self, name: str) -> None:
        self.name = name


class CatWatcher(AbstractWatcher):
    def push(self, food: Food, *args, **kwargs) -> None:
        if food.name == 'fish':
            logger.debug(f'Cat loves %s!', food.name)
        else:
            logger.debug(f'Cat hates %s!', food.name)


class MonkeyWatcher(AbstractWatcher):
    def push(self, food: Food, *args, **kwargs) -> None:
        if food.name == 'banana':
            logger.debug(f'Monkey loves %s!', food.name)
        else:
            logger.debug(f'Monkey hates %s!', food.name)


>>> food, watchers = Food(), Watchers()
>>> watchers.attach_many([CatWatcher(), MonkeyWatcher()])
<Watchers object:Observers[CatWatcher, MonkeyWatcher]>
>>> food.cook('fish')
>>> watchers.notify(food)
[watchers][DEBUG][2077-12-27 00:00:00,111] >>> Notifying watcher: CatWatcher object...
[watchers][DEBUG][2077-12-27 00:00:00,112] >>> Cat loves fish!
[watchers][DEBUG][2077-12-27 00:00:00,113] >>> Notifying watcher: MonkeyWatcher object...
[watchers][DEBUG][2077-12-27 00:00:00,114] >>> Monkey hates fish!
>>> food.cook('banana')
>>> watchers.notify(food)
[watchers][DEBUG][2077-12-27 00:00:00,115] >>> Notifying watcher: CatWatcher object...
[watchers][DEBUG][2077-12-27 00:00:00,116] >>> Cat hates banana!
[watchers][DEBUG][2077-12-27 00:00:00,117] >>> Notifying watcher: MonkeyWatcher object...
[watchers][DEBUG][2077-12-27 00:00:00,118] >>> Monkey loves banana!

Or using WatchersSpy, you can notify listeners automatically whenever a specified constraint is met, so you don't need to manually invoke notify as shown above:

from watchify import AbstractWatcher, WatchersSpy
from watchify.logger import logger

# [...]

>>> food, watchers = Food(), WatchersSpy()
>>> watchers.attach_many([CatWatcher(), MonkeyWatcher()])
<WatchersSpy object:Observers[CatWatcher, MonkeyWatcher]>
>>> watchers.spy(food, 'cook')
Spying(sender'=<Food object>', method='cook', constraint='after')
>>> food.cook('fish')
[watchers][DEBUG][2077-12-27 00:00:00,111] >>> Notifying watcher: CatWatcher object...
[watchers][DEBUG][2077-12-27 00:00:00,112] >>> Cat loves fish!
[watchers][DEBUG][2077-12-27 00:00:00,113] >>> Notifying watcher: MonkeyWatcher object...
[watchers][DEBUG][2077-12-27 00:00:00,114] >>> Monkey hates fish!
>>> food.cook('banana')
[watchers][DEBUG][2077-12-27 00:00:00,115] >>> Notifying watcher: CatWatcher object...
[watchers][DEBUG][2077-12-27 00:00:00,116] >>> Cat hates banana!
[watchers][DEBUG][2077-12-27 00:00:00,117] >>> Notifying watcher: MonkeyWatcher object...
[watchers][DEBUG][2077-12-27 00:00:00,118] >>> Monkey loves banana!