A Python implement of a ring-buffer. NOTE: Doesn't work (appendleft and append can override each other's value since resizing only appends to end)

ringbuffer.py

class RingBuffer(object):
    def __init__(self, items=None):
        self._left = 0
        self._right = 0
        self._length = 0
        self._items = []
        if items is not None:
            for item in items:
                self.append(item)

    def __len__(self):
        return self._length

    @property
    def empty(self):
        return len(self) == 0

    @property
    def left(self):
        return self._items[self._left]

    @property
    def right(self):
        return self._items[self._right]

    def _resize(self):
        self._items.extend([None] * (len(self) or 1))

    def append(self, item):
        if not self.empty:
            self._right += 1
        if len(self) >= len(self._items):
            self._resize()
        self._items[self._right] = item
        self._length += 1

    def appendleft(self, item):
        if not self.empty:
            self._left -= 1
        if len(self) >= len(self._items):
            self._resize()
        self._items[self._left] = item
        self._length += 1

    def pop(self):
        val, self._items[self._right] = self._items[self._right], None
        self._right -= 1
        self._length -= 1
        return val

    def popleft(self):
        val, self._items[self._left] = self._items[self._left], None
        self._left += 1
        self._length -= 1
        return val