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# Copyright (c) 2011 Edward Langley
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
#
# Redistributions of source code must retain the above copyright notice,
# this list of conditions and the following disclaimer.
#
# Redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in the
# documentation and/or other materials provided with the distribution.
#
# Neither the name of the project's author nor the names of its
# contributors may be used to endorse or promote products derived from
# this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
# TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
# PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
# LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
# NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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Typical usage:
@contextmanager
def some_generator(<arguments>):
<setup>
try:
yield <value>
finally:
<cleanup>
This makes this:
with some_generator(<arguments>) as <variable>:
<body>
equivalent to this:
<setup>
try:
<variable> = <value>
<body>
finally:
<cleanup>
"""
@functools.wraps(func)
def helper(*args, **kwds):
return CallableGeneratorContextManager(func(*args, **kwds))
return helper
class RegisteredObj(object):
def __init__(self, name, *args):
self.name = name
def update(self, other):
pass
def make_ctxt_manager(name):
@contextmanager
def _inner(self, name, *args):
obj = self.registry.get(name) if name in self.registry else self.child_class(name, *args)
yield obj
if obj.name not in self.registry:
self.register(obj)
_inner.__name__ = name
return _inner
import threading
class Registry(object):
child_class = None
def __setitem__(self, name, value):
with self._lock:
self.registry[name] = value
def __getitem__(self, name):
with self._lock:
return self.registry[name]
def __delitem__(self, name):
with self._lock:
del self.registry[name]
@classmethod
def reset(cls):
with cls._lock:
cls.registry.clear()
@classmethod
def get(cls, name, default=None):
with cls._lock:
return cls.registry.get(name, default)
_init_lock = threading.RLock()
@staticmethod
def setup(cls):
with cls._init_lock:
factory_name = cls.child_class.__name__.lower()
setattr(cls, factory_name, make_ctxt_manager(factory_name))
cls.registry = {}
cls._lock = threading.RLock()
return cls
def register(self, obj):
with self._lock:
old_obj = self.registry.get(obj.name)
result = obj
if old_obj is not None:
old_obj.update(obj)
result = old_obj
else:
self.registry[obj.name] = obj
return result
class DataObj(RegisteredObj):
def __init__(self, name, a):
RegisteredObj.__init__(self, name)
self.a = a
self.b = None
self.c = None
@Registry.setup
class DataObjRegistry(Registry):
child_class = DataObj
if __name__ == '__main__':
#Demo code
registry = DataObjRegistry()
with registry.dataobj('first_obj', 1) as obj1:
obj1.b = 2
with registry.dataobj('second_obj', 2) as obj2:
obj2.b = 3
obj2.c = 4
with registry.dataobj('third_obj', 3) as obj3:
obj1.b = 4
import random
def shuffled(lis):
lis = lis[:]
random.shuffle(lis)
return iter(lis)
for obj_name in shuffled(['first_obj', 'second_obj', 'third_obj']):
with registry.dataobj(obj_name) as obj:
print '%s - a: %s, b: %s, c: %s' % (obj.name, obj.a, obj.b, obj.c)
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