蟒蛇，字典即使仅保存在不同的对象上，更改也会出现在主对象上？

问题描述

即使只保存在不同的对象上，更改也会出现在主对象上？

A dict:
transportation = {"car":"ford","coche":"fiat"}

The changes:
x = transportation.setdefault("carro","BMW")

Output of the object where changes were stored(x):
BMW

Output of the original dict:
{"car":"ford","coche":"fiat","carro","BMW"}

解决方法

Dict 是可变对象。这意味着您正在为同一个字典分配一个引用。而是尝试

x = transportation.copy().setdefault("carro","BMW")

See here