Why does python not have a mechanism for data hiding?

Antoon Pardon apardon at forel.vub.ac.be
Mon Jun 2 11:38:43 CEST 2008


On 2008-05-24, Sh4wn <luckyluke56 at gmail.com> wrote:
> Hi,
>
> first, python is one of my fav languages, and i'll definitely keep
> developing with it. But, there's 1 one thing what I -really- miss:
> data hiding. I know member vars are private when you prefix them with
> 2 underscores, but I hate prefixing my vars, I'd rather add a keyword
> before it.
>
> Python advertises himself as a full OOP language, but why does it miss
> one of the basic principles of OOP? Will it ever be added to python?
>
> Thanks in advance,
> Lucas

If you really need it, you can do data hiding in python. It just
requires a bit more work.

----------------------------- Hide.py ---------------------------------
class Rec(object):
     def __init__(__, **kwargs):
         for key,value in kwargs.items():
             setattr(__, key, value)

     def __getitem__(self, key):
         return getattr(self, key)

     def __setitem__ (self, key, val):
         setattr(self, key, val)

class Foo(object):

  def __init__(self):

    hidden = Rec(x=0, y=0)

    def SetX(val):
      hidden.x = val

    def SetY(val):
      hidden.y = val

    def GetX():
      return hidden.x

    def GetY():
      return hidden.y

    self.SetX = SetX
    self.SetY = SetY
    self.GetX = GetX
    self.GetY = GetY

--------------------------------------------------------------------------
$ python
Python 2.5.2 (r252:60911, Apr 17 2008, 13:15:05) 
[GCC 4.2.3 (Debian 4.2.3-3)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> From Hide import Foo
>>> var = Foo()
>>> var.GetX()
0
>>> var.SetX(5)
>>> var.GetX()
5
>>> var.x
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'Foo' object has no attribute 'x'
>>> var.hidden.x
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'Foo' object has no attribute 'hidden'

-- 
Antoon Pardon



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