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"""
kombu.compression
=================
Object utilities.
:copyright: (c) 2009 - 2012 by Ask Solem.
:license: BSD, see LICENSE for more details.
"""
from __future__ import absolute_import
from copy import copy
from .exceptions import NotBoundError
__all__ = ["Object", "MaybeChannelBound"]
def unpickle_dict(cls, kwargs):
return cls(**kwargs)
class Object(object):
"""Common base class supporting automatic kwargs->attributes handling,
and cloning."""
attrs = ()
def __init__(self, *args, **kwargs):
any = lambda v: v
for name, type_ in self.attrs:
value = kwargs.get(name)
if value is not None:
setattr(self, name, (type_ or any)(value))
else:
try:
getattr(self, name)
except AttributeError:
setattr(self, name, None)
def setdefault(self, **defaults):
for key, value in defaults.iteritems():
if getattr(self, key) is None:
setattr(self, key, value)
def as_dict(self, recurse=False):
def f(obj):
if recurse and isinstance(obj, Object):
return obj.as_dict(recurse=True)
return obj
return dict((attr, f(getattr(self, attr))) for attr, _ in self.attrs)
def __reduce__(self):
return unpickle_dict, (self.__class__, self.as_dict())
def __copy__(self):
return self.__class__(**self.as_dict())
class MaybeChannelBound(Object):
"""Mixin for classes that can be bound to an AMQP channel."""
_channel = None
_is_bound = False
#: Defines whether maybe_declare can skip declaring this entity twice.
can_cache_declaration = False
def __call__(self, channel):
"""`self(channel) -> self.bind(channel)`"""
return self.bind(channel)
def bind(self, channel):
"""Create copy of the instance that is bound to a channel."""
return copy(self).maybe_bind(channel)
def maybe_bind(self, channel):
"""Bind instance to channel if not already bound."""
if not self.is_bound and channel:
self._channel = channel
self.when_bound()
self._is_bound = True
return self
def revive(self, channel):
"""Revive channel after the connection has been re-established.
Used by :meth:`~kombu.connection.BrokerConnection.ensure`.
"""
if self.is_bound:
self._channel = channel
self.when_bound()
def when_bound(self):
"""Callback called when the class is bound."""
pass
def __repr__(self, item=""):
if self.is_bound:
return "<bound %s of %s>" % (item or self.__class__.__name__,
self.channel)
return "<unbound %s>" % (item, )
@property
def is_bound(self):
"""Flag set if the channel is bound."""
return self._is_bound and self._channel is not None
@property
def channel(self):
"""Current channel if the object is bound."""
if self._channel is None:
raise NotBoundError(
"Can't call method on %s not bound to a channel" % (
self.__class__.__name__))
return self._channel
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