69 lines
1.6 KiB
Python
69 lines
1.6 KiB
Python
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"""Abstract classes."""
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import abc
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from collections.abc import Callable
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__all__ = ['Thenable']
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class Thenable(Callable, metaclass=abc.ABCMeta): # pragma: no cover
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"""Object that supports ``.then()``."""
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__slots__ = ()
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@abc.abstractmethod
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def then(self, on_success, on_error=None):
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raise NotImplementedError()
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@abc.abstractmethod
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def throw(self, exc=None, tb=None, propagate=True):
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raise NotImplementedError()
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@abc.abstractmethod
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def cancel(self):
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raise NotImplementedError()
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@classmethod
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def __subclasshook__(cls, C):
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if cls is Thenable:
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if any('then' in B.__dict__ for B in C.__mro__):
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return True
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return NotImplemented
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@classmethod
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def register(cls, other):
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# overide to return other so `register` can be used as a decorator
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type(cls).register(cls, other)
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return other
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@Thenable.register
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class ThenableProxy:
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"""Proxy to object that supports ``.then()``."""
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def _set_promise_target(self, p):
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self._p = p
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def then(self, on_success, on_error=None):
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return self._p.then(on_success, on_error)
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def cancel(self):
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return self._p.cancel()
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def throw1(self, exc=None):
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return self._p.throw1(exc)
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def throw(self, exc=None, tb=None, propagate=True):
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return self._p.throw(exc, tb=tb, propagate=propagate)
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@property
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def cancelled(self):
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return self._p.cancelled
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@property
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def ready(self):
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return self._p.ready
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@property
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def failed(self):
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return self._p.failed
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