Python 包的引入顺序到底是怎样的？

Question

文件结构如下:

$ tree .
.
├── main.py
├── os.py
└── platform.py

main.py:

import platform
import os
import sys
print('Now in main, Start`enter code here` to Exec following')
print(os.getcwd())
print(sys.modules['platform'].__file__)
print(platform.processor())

os.py:

print('Now in os.py module')

platform.py:

print('Now in platform.py module')

当我运行 python main.py，结果如下:

$ python main.py
Now in platform.py module
Now in main, Start to Exec following
/Users/michael/Code/00-Temp/pkg_import
/Users/michael/Code/00-Temp/pkg_import/platform.py
Traceback (most recent call last):
  File "main.py", line 9, in <module>
    print(platform.processor())
AttributeError: module 'platform' has no attribute 'processor'

问题1：os 和 platform 都是内置模块, 当 import os，默认走到了内置模块,但是 import platform, 却获取了同级目录下的 plarform，为何出现这个现象呢？

问题2：同样的脚本，我在 Pycharm 中直接运行 main.py ，却报这个错误：

/Users/michael/anaconda3/bin/python /Users/michael/Code/00-Temp/pkg_import/main.py
Now in os.py module
Fatal Python error: initsite: Failed to import the site module
Traceback (most recent call last):
  File "/Users/michael/anaconda3/lib/python3.7/site.py", line 570, in <module>
    main()
  File "/Users/michael/anaconda3/lib/python3.7/site.py", line 547, in main
    known_paths = removeduppaths()
  File "/Users/michael/anaconda3/lib/python3.7/site.py", line 126, in removeduppaths
    dir, dircase = makepath(dir)
  File "/Users/michael/anaconda3/lib/python3.7/site.py", line 91, in makepath
    dir = os.path.join(*paths)
AttributeError: module 'os' has no attribute 'path'

Process finished with exit code 1

Answer 1

如果是python环境那么，导包会先从同级目录去找你导入的模块。如果找不到，回去python内置的第三方包去查找模块。完整的查找方式为：同级方法<--同级模块<--同级包<--第三方包

Answer 2

python 运行时会预转载一些module，你用sys.modules print 一下就知道了。如果已经加载就不会再有搜索一说了～