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To: python-list@python.org
From: Dennis Lee Bieber <wlfraed@ix.netcom.com>
Subject: Re: Classes
Date: Fri, 31 Oct 2014 18:26:02 -0400
Organization: IISS Elusive Unicorn
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On Fri, 31 Oct 2014 12:31:56 -0400, Seymore4Head
<Seymore4Head@Hotmail.invalid> declaimed the following:

>
>In this class, we will follow the practice of accessing the contents
>of objects using methods known as getters and setters. While not
>required by Python, this practice encourages the user of the class to
>manipulates class objects solely via class methods. The advantage of
>following this practice is that the implementer of the class
>definition (often someone other than the user of the class) may
>restructure the organization of the data fields associated with the
>object while avoiding the need to rewrite code that uses the class.

	In Python, the conversion of direct attributes into properties does
exactly that -- NO REWRITE of using code...

	What you are being taught is NOT PYTHON.

-=-=-=-=-=-=-
def user():
    mySomething = Something()
    print mySomething.who
    print id(mySomething), id(Something)
    print mySomething.X
    mySomething.X = 123
    print mySomething.X
    print "********"
    

class Something(object):
    def __init__(self):
        self.X = None
        self.who = "I am the direct access version"

user()  #invoke a user with first class definition

#now redefine the class with properties
class Something(object):
    def __init__(self):
        self._X = None
        self.who = "I am the property version with getter/setter"
    def _setX(self, vlu):
        self._X = vlu
    def _getX(self):
        return self._X
    X = property(_getX, _setX)

user()  #invoke the SAME USER CODE but with class now using properties
-=-=-=-=-=-=-
Microsoft Windows [Version 6.1.7601]
Copyright (c) 2009 Microsoft Corporation.  All rights reserved.

C:\Users\Wulfraed\Documents>cd "Python Progs"

C:\Users\Wulfraed\Documents\Python Progs>property.py
I am the direct access version
35663488 35817816
None
123
********
I am the property version with getter/setter
35663488 35818760
None
123
********

C:\Users\Wulfraed\Documents\Python Progs>

-- 
	Wulfraed                 Dennis Lee Bieber         AF6VN
    wlfraed@ix.netcom.com    HTTP://wlfraed.home.netcom.com/