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from threading import RLock
from typing import Optional
from reactivex.abc import DisposableBase
class MultipleAssignmentDisposable(DisposableBase):
"""Represents a disposable resource whose underlying disposable
resource can be replaced by another disposable resource."""
def __init__(self) -> None:
self.current: Optional[DisposableBase] = None
self.is_disposed = False
self.lock = RLock()
super().__init__()
def get_disposable(self) -> Optional[DisposableBase]:
return self.current
def set_disposable(self, value: DisposableBase) -> None:
"""If the MultipleAssignmentDisposable has already been
disposed, assignment to this property causes immediate disposal
of the given disposable object."""
with self.lock:
should_dispose = self.is_disposed
if not should_dispose:
self.current = value
if should_dispose and value is not None:
value.dispose()
disposable = property(get_disposable, set_disposable)
def dispose(self) -> None:
"""Disposes the underlying disposable as well as all future
replacements."""
old = None
with self.lock:
if not self.is_disposed:
self.is_disposed = True
old = self.current
self.current = None
if old is not None:
old.dispose()
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