pool.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

"""http://stackoverflow.com/questions/1514120/python-implementation-of-the-object-pool-design-pattern"""


class QueueObject():

 def __init__(self, queue, auto_get=False):
 self._queue = queue
 self.object = self._queue.get() if auto_get else None

 def __enter__(self):
 if self.object is None:
 self.object = self._queue.get()
 return self.object

 def __exit__(self, Type, value, traceback):
 if self.object is not None:
 self._queue.put(self.object)
 self.object = None

 def __del__(self):
 if self.object is not None:
 self._queue.put(self.object)
 self.object = None


def main():
 try:
 import queue
 except ImportError: # python 2.x compatibility
 import Queue as queue

 def test_object(queue):
 queue_object = QueueObject(queue, True)
 print('Inside func: {}'.format(queue_object.object))

 sample_queue = queue.Queue()

 sample_queue.put('yam')
 with QueueObject(sample_queue) as obj:
 print('Inside with: {}'.format(obj))
 print('Outside with: {}'.format(sample_queue.get()))

 sample_queue.put('sam')
 test_object(sample_queue)
 print('Outside func: {}'.format(sample_queue.get()))

 if not sample_queue.empty():
 print(sample_queue.get())


if __name__ == '__main__':
 main()

### OUTPUT ###
# Inside with: yam
# Outside with: yam
# Inside func: sam
# Outside func: sam