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
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。
其他回答
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。
In Python, "privacy" depends on "consenting adults'" levels of agreement - you can't force it (any more than you can in real life;-). A single leading underscore means you're not supposed to access it "from the outside" -- two leading underscores (w/o trailing underscores) carry the message even more forcefully... but, in the end, it still depends on social convention and consensus: Python's introspection is forceful enough that you can't handcuff every other programmer in the world to respect your wishes.
((顺便说一下，虽然这是一个严格保密的秘密，但对于c++来说也是如此:在大多数编译器中，在#包括你的.h文件之前，一个简单的#define private public line就可以让狡猾的编码器对你的“隐私”进行散列…!-))
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
Python有三种模式via。当导入一个模块时，只有public模式是可访问的。因此private和protected模块不能从模块外部调用，即当它被导入时。
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).
