根据http://www.faqs.org/docs/diveintopython/fileinfo_private.html:

像大多数语言一样,Python具有 私有元素的概念: 私人 函数,这些函数不能被调用 在模块外

然而,如果我定义两个文件:

#a.py
__num=1

and:

#b.py
import a
print a.__num

当我运行b.py时,它输出1而不给出任何异常。是diveintopython错了,还是我误解了什么?是否有方法将模块的函数定义为私有?


当前回答

Python允许带有双下划线前缀的私有类成员。这种技术在模块级别上不起作用,所以我认为这是Dive Into Python中的一个错误。

下面是一个私有类函数的例子:

class foo():
    def bar(self): pass
    def __bar(self): pass

f = foo()
f.bar()   # this call succeeds
f.__bar() # this call fails

其他回答

Python允许带有双下划线前缀的私有类成员。这种技术在模块级别上不起作用,所以我认为这是Dive Into Python中的一个错误。

下面是一个私有类函数的例子:

class foo():
    def bar(self): pass
    def __bar(self): pass

f = foo()
f.bar()   # this call succeeds
f.__bar() # this call fails

嵌入闭包或函数是一种方法。这在JS中很常见,但对于非浏览器平台或浏览器worker来说不是必需的。

在Python中,这似乎有点奇怪,但如果确实需要隐藏一些东西,那可能是一种方法。更重要的是,使用python API并将需要隐藏在C(或其他语言)中的内容可能是最好的方法。如果做不到这一点,我会把代码放在一个函数中,调用它,让它返回你想要导出的项。

抱歉我回答晚了,但是在一个模块中,你可以像这样定义包来“导出”:

mymodule
  __init__.py
  library.py
main.py

我的模块/库.py

# 'private' function
def _hello(name):
    return f"Hello {name}!"

# 'public' function which is supposed to be used instead of _hello
def hello():
    name = input('name: ')
    print(_hello(name))

mymodule里/ __init__ . py

# only imports certain functions from library
from .library import hello

main.py

import mymodule
mymodule.hello()

尽管如此,函数仍然可以被访问,

from mymodule.library import _hello
print(_hello('world'))

但这种方法使其不那么明显

见PEP8指南:

方法名称和实例变量

Use the function naming rules: lowercase with words separated by underscores as necessary to improve readability. Use one leading underscore only for non-public methods and instance variables. To avoid name clashes with subclasses, use two leading underscores to invoke Python’s name mangling rules. Python mangles these names with the class name: if class Foo has an attribute named __a, it cannot be accessed by Foo.__a. (An insistent user could still gain access by calling Foo._Foo__a.) Generally, double leading underscores should be used only to avoid name conflicts with attributes in classes designed to be subclassed.

为传承而设计

Always decide whether a class’s methods and instance variables (collectively: “attributes”) should be public or non-public. If in doubt, choose non-public; it’s easier to make it public later than to make a public attribute non-public. Public attributes are those that you expect unrelated clients of your class to use, with your commitment to avoid backwards incompatible changes. Non-public attributes are those that are not intended to be used by third parties; you make no guarantees that non-public attributes won’t change or even be removed. We don’t use the term “private” here, since no attribute is really private in Python (without a generally unnecessary amount of work).

你可以添加一个内部函数:

def public(self, args):
   def private(self.root, data):
       if (self.root != None):
          pass #do something with data

如果你真的需要那种程度的隐私的话。