Python 嵌套包：AttributeError:module'；app&x27；没有属性

我刚刚学习python，来自C#和Java背景，我对导入系统感到非常困惑。只是为了学习而尝试运行一个简单的测试，但是获取一个错误属性error:module“app”没有属性“example”

请参阅下面的代码，是否有人可以解释引发错误的原因？我似乎只有在包中有包时才会遇到这个问题，如包“app”中包含的包“example”实例所示

run.py

import app

import app.example

import app.example.a

import app.example.b
print("TESTING: " + str(app.example.b)) #error is thrown on this line

print("LOADED B")

app/\uuuu init\uuuuu.py

import app

import app.example

import app.example.a

import app.example.b
print("TESTING: " + str(app.example.b)) #error is thrown on this line

print("LOADED B")

app/example/\uuuuu init\uuuuuuu.py

import app

import app.example

import app.example.a

import app.example.b
print("TESTING: " + str(app.example.b)) #error is thrown on this line

print("LOADED B")

app/example/a.py

import app

import app.example

import app.example.a

import app.example.b
print("TESTING: " + str(app.example.b)) #error is thrown on this line

print("LOADED B")

app/example/b.py

import app

import app.example

import app.example.a

import app.example.b
print("TESTING: " + str(app.example.b)) #error is thrown on this line

print("LOADED B")

引发错误：

"C:\Program Files\Python 3.5\npwc-services\Scripts\python.exe" C:/Users/xxxxxxxx/PycharmProjects/untitled1/run.py
Traceback (most recent call last):
LOADED B
  File "C:/Users/xxxxxxxx/PycharmProjects/untitled1/run.py", line 1, in <module>
    import app
  File "C:\Users\xxxxxxxx\PycharmProjects\untitled1\app\__init__.py", line 1, in <module>
    import app.example
  File "C:\Users\xxxxxxxx\PycharmProjects\untitled1\app\example\__init__.py", line 1, in <module>
    import app.example.a
  File "C:\Users\xxxxxxxx\PycharmProjects\untitled1\app\example\a.py", line 2, in <module>
    print("TESTING: " + str(app.example.b))
AttributeError: module 'app' has no attribute 'example'

Process finished with exit code 1

“C:\Program Files\Python 3.5\npwc services\Scripts\Python.exe”C:/Users/xxxxxxxx/pycharm项目/untitled1/run.py
回溯（最近一次呼叫最后一次）：
负载B
文件“C:/Users/xxxxxxxx/PycharmProjects/untitled1/run.py”，第1行，在
导入应用程序
文件“C:\Users\xxxxxxxx\PycharmProjects\untitled1\app\\uuuuu init\uuuuuuuu.py”，第1行，在
导入app.example
文件“C:\Users\xxxxxxxx\PycharmProjects\untitled1\app\example\\uuuuu init\uuuuuu.py”，第1行，在
导入app.example.a
文件“C:\Users\xxxxxxxx\PycharmProjects\untitled1\app\example\a.py”，第2行，在
打印（“测试：+str（应用示例b））
AttributeError:模块“app”没有属性“example”
进程已完成，退出代码为1

目录结构：

"C:\Program Files\Python 3.5\npwc-services\Scripts\python.exe" C:/Users/xxxxxxxx/PycharmProjects/untitled1/run.py
Traceback (most recent call last):
LOADED B
  File "C:/Users/xxxxxxxx/PycharmProjects/untitled1/run.py", line 1, in <module>
    import app
  File "C:\Users\xxxxxxxx\PycharmProjects\untitled1\app\__init__.py", line 1, in <module>
    import app.example
  File "C:\Users\xxxxxxxx\PycharmProjects\untitled1\app\example\__init__.py", line 1, in <module>
    import app.example.a
  File "C:\Users\xxxxxxxx\PycharmProjects\untitled1\app\example\a.py", line 2, in <module>
    print("TESTING: " + str(app.example.b))
AttributeError: module 'app' has no attribute 'example'

Process finished with exit code 1

run.py

import app

app/init.py

from .example.app import a # or b or ...

---

在

app/\uuuuu init\uuuuuu.py

中尝试

import.example

，并在其他模块和软件包中执行此操作。在包中需要相对导入，而不是绝对导入。谢谢，直到你提到它，我才知道相对导入是可能的，但是你提供的确切语法在Python 3中不适用。我不得不这样做：from.example.app导入一个更正，我最终使用from。导入示例，该示例似乎与您在评论中提供的内容直接等效。