python - 一切都大于无吗？

Question

除了 None 之外，是否还有 Python 内置数据类型:

>>> not foo > None
True

foo 是那种类型的值？ Python 3 怎么样？

Answer 1

None总是小于 Python 2 中的任何数据类型(参见 object.c )。

在 Python 3 中，这已更改；现在对没有合理自然排序的事物进行比较会导致 TypeError .来自 3.0 "what's new" updates :

Python 3.0 has simplified the rules for ordering comparisons:

The ordering comparison operators (<, <=, >=, >) raise a TypeError exception when the operands don’t have a meaningful natural ordering. Thus, expressions like: 1 < '', 0 > None or len <= len are no longer valid, and e.g. None < None raises TypeError instead of returning False. A corollary is that sorting a heterogeneous list no longer makes sense – all the elements must be comparable to each other. Note that this does not apply to the == and != operators: objects of different incomparable types always compare unequal to each other.

这让一些人感到不安，因为对包含一些 None 的列表进行排序之类的操作通常很方便。值，并具有 None值在开始或结束时聚集在一起。 There was a thread on the mailing list about this 不久前，但最终的一点是 Python 3 试图避免对排序做出任意决定(这在 Python 2 中经常发生)。