Are there Python code for a FIFO-like structure?

[Aahz Maruch]

In article <slrn8ts14c.pu.hzhu at rocket.knowledgetrack.com>,
Huaiyu Zhu <hzhu at users.sourceforge.net> wrote:
>
>The fixed length requirement is meant to limit its growth and raise error
>when it's full, at that time several different actions might be taken. The
>rotation requirement is so that it's light weight even if it's large.

Unless large means >1000, I'd suggest you not waste time on it.  One
option for simplicity might be to just use a dictionary with a unique
value for each item.  Here's a sketch, not complete:

class dict_queue:
  def __init__ (self, max_size):
    self.max_size = max_size
    self.min = None
    self.max = None
    self.queue = {}
  def put(self, item):
    if (self.max - self.min) >= self.max_size:
	raise ValueError, "Too many items in queue"
    self.max = self.max + 1
    self.queue[self.max] = item
  def get(self):
    tmp = self.queue[self.min]
    del queue[self.min]
    self.min = self.min - 1
    return tmp
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