Array?

[George Sakkis]

Dr. Pastor wrote:

> I need a row of 127 bytes that I will use as a
> circular buffer. Into the bytes (at unspecified times)
> a mark (0<mark<128) will be written, one after the other.
> After some time the "buffer" will contain the last 127 marks
> and a pointer will point the next "usable" byte.
> What would be the Pythonic way to do the above?
> Thanks for any guidance.

This will do the trick:

import itertools as it
from array import array

class CircularBuffer(object):
    def __init__(self, size=128):
        self._buffer = array('c', it.repeat(chr(0),size))
        self._next = 0

    def putmark(self, mark):
        self._buffer[self._next] = mark
        self._next = (self._next+1) % len(self._buffer)

    def __str__(self):
        return '%s(%r)' % (self.__class__.__name__,
                                   self._buffer.tostring())


if __name__ == '__main__':
    import string
    b = CircularBuffer()
    for c in string.letters * 10:
        b.putmark(c)
        print b


HTH,
George