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# module1.py

question = "What is the meaning of life, the Universe, and everything?"
answer = 42


# module2.py

question = "What is your quest?"
answer = "To seek the holy grail."




>>> import module1
>>> import module2
>>> print module1.question
What is the meaning of life, the Universe, and everything?
>>> print module2.question
What is your quest?
>>> print module1.answer
42
>>> print module2.answer
To seek the holy grail.

如果我们使用 from module1 import * 和 from module2 import * 代替，我们将发生命名冲突，并且无法访问来自 module1 的问题和答案。为什么会这样？

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2 回答 2

3

一个基于@alexce 示例的简单示例：

>>> pi = 22/7
>>> pi
3

当前在全局命名空间中定义的变量：

>>> vars()
{'__builtins__': <module '__builtin__' (built-in)>, '__name__': '__main__', 'pi': 3, '__doc__': None, '__package__': None}

现在我们进行*基于导入：

>>> from math import *

新pi从math取代旧pi

>>> pi
3.141592653589793

现在全局命名空间充满了数学模块的变量：

>>> vars()
{'pow': <built-in function pow>, 'fsum': <built-in function fsum>, 'cosh': <built-in function cosh>, 'ldexp': <built-in function ldexp>, 'hypot': <built-in function hypot>, 'acosh': <built-in function acosh>, 'tan': <built-in function tan>, 'asin': <built-in function asin>, 'isnan': <built-in function isnan>, 'log': <built-in function log>, 'fabs': <built-in function fabs>, 'floor': <built-in function floor>, 'atanh': <built-in function atanh>, 'sqrt': <built-in function sqrt>, '__package__': None, 'frexp': <built-in function frexp>, 'factorial': <built-in function factorial>, 'degrees': <built-in function degrees>, 'pi': 3.141592653589793, 'log10': <built-in function log10>, '__doc__': None, 'asinh': <built-in function asinh>, 'fmod': <built-in function fmod>, 'atan': <built-in function atan>, '__builtins__': <module '__builtin__' (built-in)>, 'copysign': <built-in function copysign>, 'cos': <built-in function cos>, 'ceil': <built-in function ceil>, 'atan2': <built-in function atan2>, 'isinf': <built-in function isinf>, 'sinh': <built-in function sinh>, '__name__': '__main__', 'trunc': <built-in function trunc>, 'expm1': <built-in function expm1>, 'e': 2.718281828459045, 'tanh': <built-in function tanh>, 'radians': <built-in function radians>, 'sin': <built-in function sin>, 'lgamma': <built-in function lgamma>, 'erf': <built-in function erf>, 'erfc': <built-in function erfc>, 'modf': <built-in function modf>, 'exp': <built-in function exp>, 'acos': <built-in function acos>, 'log1p': <built-in function log1p>, 'gamma': <built-in function gamma>}

因此，这样的导入将替换所有已在全局命名空间中定义的同名变量。

来自文档：

请注意，通常不赞成*从模块或包导入的做法，因为它通常会导致代码可读性差。但是，可以使用它来节省交互式会话中的输入。

于 2013-09-01T19:51:54.087 回答
2 
x = 'foo'
x = 'bar'
print x

这就是为什么。

于 2013-09-01T19:43:06.483 回答