When class instances are unpickled, their _init_() method isn't normally called again.

当 unpickle 类的实例时，通常不会再调用它们的 _init_() 方法。

youdao

First, leave the original class definition intact so that it can be found when existing instances are unpickled.

首先，确保原来的类的定义没有被更改，以便在unpickle现有实例时可以找到它。

youdao

Once you are sure that all the existing instances have been unpickled, updated, and re-pickled, you can remove the old class definition from the source code module.

一旦确定所有现有的实例都已经unpickle、更新和重新pickle后，可以从源代码模块中除去旧的类定义。

youdao