Jython: deque() does not take keyword arguments

[eandersson]

There is unfortunately another issue with Jython that I missed when submitting the previous fixes in #440, related to Issue #370.

Caused by this bug in Jython http://bugs.jython.org/issue1949

Traceback

Traceback (most recent call last):
  File "C:/Users/eandersson/Desktop/pika-master/test.py", line 7, in <module>
    channel = connection.channel()
  File "C:\Users\eandersson\Desktop\pika-master\pika\adapters\blocking_connection.py", line 195, in channel
    self._channels[channel_number] = BlockingChannel(self, channel_number)
  File "C:\Users\eandersson\Desktop\pika-master\pika\adapters\blocking_connection.py", line 452, in __init__
    super(BlockingChannel, self).__init__(connection, channel_number)
  File "C:\Users\eandersson\Desktop\pika-master\pika\channel.py", line 77, in __init__
    self._cancelled = collections.deque(list(), maxlen=10)
TypeError: deque() does not take keyword arguments

Possible solutions

First one way could cause unexpected behavior under Jython.

        try:
            self._cancelled = collections.deque(list(), maxlen=10)
        except TypeError:
            self._cancelled = collections.deque(list())

Second one would need to be wrapped around any append call and make it difficult to maintain the code.

if len(self._cancelled) >= 10:
    self.popleft()

Third one would need to cover all options adding to the dequeue, but most likely be the cleanest solution.

class deque_wrapper(collections.deque):
    """Compatibility wrapper around deque to fix a Jython issue.

        http://bugs.jython.org/issue1949
    """
    def __init__(self, iterable=(), maxlen=None):
        try:
            super(deque_wrapper, self).__init__(iterable, maxlen=maxlen)
        except TypeError:
            self._maxlen = maxlen
            super(deque_wrapper, self).__init__(iterable)

    def append(self, *args, **kwargs):
        if hasattr(self, '_maxlen'):
            if len(self) >= self._maxlen:
                self.popleft()
        super(deque_wrapper, self).append(*args, **kwargs)

[gmr]

This should address that for you, LMK.

[eandersson]

Looks good thanks.