不返回包名的dunder属性

Question

只是想要获得给定模块的包名，为什么Just 包属性不能工作？

import sys, inspect, os, numpy as np
print("The os package name is " + os.__package__)
print("The np package name is " + np.__package__)
print("The inspect package name is " + inspect.__package__)
print("The sys package name is " + sys.__package__) 

我从上面得到的信息如下。

The os package name is 
The np package name is numpy
The inspect package name is 
The sys package name is

如您所见，它只对numpy有效，而对其他人不起作用。有人能告诉我为什么吗？我遗漏了什么？

Answer 1

查看PEP366

还可以查看另一个StackOverflow post whats-the-purpose-of-the-package-attribute-in-python