Python属性

考虑到下面的代码,输出似乎有点可疑。为什么“进入基地”只打印一次?为什么根本不打印“固定在底座上”?不过,实际的获取/设置似乎很好。我错过了什么?

class Base:
    def __init__(self):
        self.s = "BaseStr"

    def getstr(self):
        print "get in Base"
        return self.s
    def setstr(self, s):
        print "set in Base"
        self.s = s
    str = property(getstr, setstr)

b = Base()
print b.str
b.str = "Foo"
print b.str

get in Base
BaseStr
Foo