[Tutor] Protected methods/variables

[Kent Johnson]

w chun wrote:
>> I have missed protected method/variables in Python. How do you declare
>> methods/variables used only by a class and their derived classes?
> 
> hi Ktalà,
> 
> welcome to Python!  you missed "protection" in OOP with Python bceause
> there are no such declarations in Python!
> 
> 1) there is a privacy *hint*, which is using "__" to start a variable
> or method name with, e.g.,  def __myMaybePrivateMethod(self,...). 
> this does name-mangle the attribute at run-time, however the algorithm
> is fairly well-known and easy to crack:
> self._CLASS__myMaybePrivateMethod().  for more on this see,:
> http://docs.python.org/tut/node11.html#SECTION0011600000000000000000

1a) start a variable name with _ which is a hint to users of the class 
that the variable is for internal use only.

> - you can use __slots__ to restrict arbirtrary creation of (dynamic)
> instrance attributes

You can do this, but it is generally considered a misuse of __slots__ 
and potentially problematic.


Python takes the attitude that "we're all adults here" and doesn't try 
to hide anything. The _ naming convention is part of this culture - you 
tell the users to keep hands off, but if they don't, on their head be it!

Kent