在Python中，要为“重写”重写哪个运算符；if object:“；？

我发现使用以下构造检查对象是否为“空”非常方便：

l=[]
if l:
     do_stuff()

对于标准python列表，仅当列表不为空时才会执行

if

---

我的问题是，如何为我自己的对象实现相同的想法？

定义一个方法

\uuubool\uuuu

（Python3.x）或

\uuu nonzero\uuuu

（2.x）。或者为可移植性定义两者，其中一个返回另一个的结果。

为Python 2和Python 3实现：

class AlwaysTrueObject:
    def __bool__(self):
        return True
    __nonzero__ = __bool__

---

如果您实现

\uuu len\uuuu

Python将为您实现这一点，前提是长度为0意味着对象的布尔值为

False

，否则它的布尔值为

True

---

如果在3.x中实现

\uuuu len\uuuuu

没有意义，您可以实现

\uuu非零

（或

\uuuuu bool\uuuuu

在3.x中（只有名称已更改）），它应该根据对象的布尔值返回

True

或

False

。

谢谢！两者之间有区别吗？我相信

\uuubool\uuu

是后来添加的。它们应该执行相同的操作，通过一个调用另一个来定义两者应该是安全的。

\uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu>是Python 2.x，
\uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu。我想
\uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu。我同意，如果len已经在那里并完成了任务，那么实施bool是没有意义的。