[Tutor] designing POOP

[Dave Kuhlman]

On Sat, Feb 09, 2008 at 08:42:04PM -0500, Kent Johnson wrote:
> Alan Gauld wrote:
> 
> >>   def values(self):
> >>     return (self.name, self.wealth, self.strenth)
> >>
> >> Or get rid of values() entirely and just refer to the attributes
> > 
> > Nope, I don't like that as much since it encourages direct
> > access. 
> 
> Maybe we just need to agree to disagree here. I don't see how returning 
> a tuple is better encapsulation than direct access to named attributes.

Here is something relevant to this argument, although I'm not sure
that I agree with it:

    "Getters and setters are evil. Evil, evil, I say! Python objects
    are not Java beans. Do not write getters and setters. This is
    what the 'property' built-in is for. And do not take that to
    mean that you should write getters and setters, and then wrap
    them in 'property'. That means that until you prove that you
    need anything more than a simple attribute access, don't write
    getters and setters. They are a waste of CPU time, but more
    important, they are a waste of programmer time. Not just for
    the people writing the code and tests, but for the people who
    have to read and understand them as well.

    "In Java, you have to use getters and setters because using
    public fields gives you no opportunity to go back and change
    your mind later to using getters and setters. So in Java, you
    might as well get the chore out of the way up front. In Python,
    this is silly, because you can start with a normal attribute
    and change your mind at any time, without affecting any clients
    of the class. So, don't write getters and setters."

       extracted from:
          http://dirtsimple.org/2004/12/python-is-not-java.html

Maybe I'm "old school", but I still use getters and setters for
access from outside the class and direct access from within methods
in the class.

- Dave

[some good arguments snipped]


-- 
Dave Kuhlman
http://www.rexx.com/~dkuhlman