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- from dataclasses import dataclass
- from functools import wraps
- from typing import Any, Callable, Iterator, List, Type, TypeVar
- from pyee import EventEmitter
- @dataclass
- class Handler:
- event: str
- method: Callable
- class Handlers:
- def __init__(self) -> None:
- self._handlers: List[Handler] = []
- def append(self, handler) -> None:
- self._handlers.append(handler)
- def __iter__(self) -> Iterator[Handler]:
- return iter(self._handlers)
- def reset(self):
- self._handlers = []
- _handlers = Handlers()
- def on(event: str) -> Callable[[Callable], Callable]:
- """
- Register an event handler on an evented class. See the `evented` class
- decorator for a full example.
- """
- def decorator(method: Callable) -> Callable:
- _handlers.append(Handler(event=event, method=method))
- return method
- return decorator
- def _bind(self: Any, method: Any) -> Any:
- @wraps(method)
- def bound(*args, **kwargs) -> Any:
- return method(self, *args, **kwargs)
- return bound
- Cls = TypeVar("Cls", bound=Type)
- def evented(cls: Cls) -> Cls:
- """
- Configure an evented class.
- Evented classes are classes which use an EventEmitter to call instance
- methods during runtime. To achieve this without this helper, you would
- instantiate an `EventEmitter` in the `__init__` method and then call
- `event_emitter.on` for every method on `self`.
- This decorator and the `on` function help make things look a little nicer
- by defining the event handler on the method in the class and then adding
- the `__init__` hook in a wrapper:
- ```py
- from pyee.cls import evented, on
- @evented
- class Evented:
- @on("event")
- def event_handler(self, *args, **kwargs):
- print(self, args, kwargs)
- evented_obj = Evented()
- evented_obj.event_emitter.emit(
- "event", "hello world", numbers=[1, 2, 3]
- )
- ```
- The `__init__` wrapper will create a `self.event_emitter: EventEmitter`
- automatically but you can also define your own event_emitter inside your
- class's unwrapped `__init__` method. For example, to use this
- decorator with a `TwistedEventEmitter`::
- ```py
- @evented
- class Evented:
- def __init__(self):
- self.event_emitter = TwistedEventEmitter()
- @on("event")
- async def event_handler(self, *args, **kwargs):
- await self.some_async_action(*args, **kwargs)
- ```
- """
- handlers: List[Handler] = list(_handlers)
- _handlers.reset()
- og_init: Callable = cls.__init__
- @wraps(cls.__init__)
- def init(self: Any, *args: Any, **kwargs: Any) -> None:
- og_init(self, *args, **kwargs)
- if not hasattr(self, "event_emitter"):
- self.event_emitter = EventEmitter()
- for h in handlers:
- self.event_emitter.on(h.event, _bind(self, h.method))
- cls.__init__ = init
- return cls
|
