'__getnewargs__'在这段代码中做了什么

Question

class NavigableString(unicode, PageElement):

    def __new__(cls, value):
        if isinstance(value, unicode):
            return unicode.__new__(cls, value)
        return unicode.__new__(cls, value, DEFAULT_OUTPUT_ENCODING)

    def __getnewargs__(self):#this line
        return (NavigableString.__str__(self),)

Answer 1

试试这个：

x = NavigableString('foop')
y = pickle.dumps(x)
z = pickle.loads(y)
print x, z

即：__getnewargs__告诉pickle.dumps挑选x，以便从该字符串返回的pickle.loads将NavigableString.__new__与正确的参数一起使用。