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Date: Sun, 01 Sep 2013 13:33:25 -0700
From: Ethan Furman <ethan@stoneleaf.us>
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To: python-list@python.org
Subject: Re: Encapsulation unpythonic?
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On 09/01/2013 12:13 PM, Roy Smith wrote:
> In article <mailman.455.1378062400.19984.python-list@python.org>,
>   Ethan Furman <ethan@stoneleaf.us> wrote:
>
>> On 09/01/2013 03:09 AM, Fabrice Pombet wrote:
>>>
>>> So I guess that we are actually all agreeing on this one.
>>
>> No, we are not.
>>
>> "encapsulation" != "inaccessible except by getters/setters"
>
> Nothing is accessible in Python except via getters and setters.  The
> only difference between Python and, say, C++ in this regard is that the
> Python compiler writes them for you most of the time and doesn't make
> you put ()'s at the end of the name :-)

class Javaesque:

     __value = None

     def get_value(self):
         return self.__value

     def set_value(self, new_value):
         validate(new_value)
         self.__value = new_value


class ProtectedPython:

     _value = None

     @property
     def value(self):
         return self._value

     @value.setter
     def value(self, new_value)
         validate(new_value)
         self._value = new_value

class PlainPython:

     value = None


In the Javaesque class we see the unPythonic way of using getters/setters; in the ProtectedPython* class we see the 
pythonic way of providing getters/setters**; in the PlainPython class we have the standard, unprotected, direct access 
to the class attribute.

No where in PlainPython is a getter/setter defined, nor does Python define one for us behind our backs.

If you have evidence to the contrary I'd like to see it.


* Not the best name, but oh well.
** In Python, using @property makes getter/setter usage look just like normal attribute usage, which is cool.

--
~Ethan~