ordereddict.py 文件源码

def setdefault(self, key, value):
        """If key is in the dictionary, returns its value;
        otherwise adds the key with the given value which is also
        returned

        >>> d = OrderedDict(dict(s=1, a=2, n=3, i=4, t=5, y=6))
        >>> d.setdefault("n", 99)
        3
        >>> d.values()
        [2, 4, 3, 1, 5, 6]
        >>> d.setdefault("r", -20)
        -20
        >>> d.items()[2:]
        [('n', 3), ('r', -20), ('s', 1), ('t', 5), ('y', 6)]
        >>> d.setdefault("@", -11)
        -11
        >>> d.setdefault("z", 99)
        99
        >>> d.setdefault("m", 50)
        50
        >>> d.keys()
        ['@', 'a', 'i', 'm', 'n', 'r', 's', 't', 'y', 'z']
        """
        if key not in self.__dict:
            bisect.insort_left(self.__keys, key)
        return self.__dict.setdefault(key, value)