减少和减少的区别是什么？

Question

我知道这些方法是用于pickling/unpickling的，与reduce内置函数没有关系，但是2之间的区别是什么？为什么我们需要两者？

Answer 1

The docs说吧

If provided, at pickling time __reduce__() will be called with no arguments, and it must return either a string or a tuple.

另一方面

It is sometimes useful to know the protocol version when implementing __reduce__. This can be done by implementing a method named __reduce_ex__ instead of __reduce__. __reduce_ex__, when it exists, is called in preference over __reduce__ (you may still provide __reduce__ for backwards compatibility). The __reduce_ex__ method will be called with a single integer argument, the protocol version.

在紧握的手上，Guido says这是一个可以清理的区域。

Answer 2

__reduce_ex__是__reduce__本应但从未成为的。__reduce_ex__的工作方式与__reduce__类似，但pickle协议已通过。