gistfile1.py

# coding: utf-8

class Q(object):
    """
    >>> q = Q(2)
    >>> q.put('a', 1)
    >>> q.put('b', 2)
    >>> q.put("c", 3)
    >>> q.get("a")
    >>> q.get('b')
    2
    >>> q.get('c')
    3
    >>> q.get('d')
    """

    def __init__(self, size):
        self.size = size
        self.keys = []
        self.data = {}

    def put(self, key, val):
        if len(self.data) >= self.size:
            del self.data[self.keys[0]]
            self.keys = self.keys[1:]
        self.keys.append(key)
        self.data[key] = val


    def get(self, key):
        if key in self.data:
            pop = self.keys.pop(self.keys.index(key))
            self.keys.append(pop)
            return self.data[key]
        return None

if __name__ == '__main__':
    import doctest
    doctest.testmod()