python模块中名称空间的命名冲突

2024-03-29 11:02:40 发布

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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*,则会出现命名冲突,无法访问来自module1的问题和答案。为什么会这样?你知道吗


Tags: andoftheanswerpyimportiswhat
2条回答
x = 'foo'
x = 'bar'
print x

这就是为什么。你知道吗

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*的导入:

>>> from math import *

来自math的新pi替换旧的pi

>>> pi
3.141592653589793

现在,全局名称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,这样的导入将替换已在全局命名空间中定义的具有相同名称的所有变量。你知道吗

docs

Note that in general the practice of importing * from a module or package is frowned upon, since it often causes poorly readable code. However, it is okay to use it to save typing in interactive sessions.

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