Classes

[Seymore4Head]

On Fri, 31 Oct 2014 18:57:31 -0400, Dennis Lee Bieber
<wlfraed at ix.netcom.com> wrote:

>On Fri, 31 Oct 2014 14:18:44 -0400, Seymore4Head
><Seymore4Head at Hotmail.invalid> declaimed the following:
>
>>On Fri, 31 Oct 2014 10:43:19 -0700, Rob Gaddi
>><rgaddi at technologyhighland.invalid> wrote:
>>
>>
>>>Define a Square class, subclassed from Rectangle.  Use getters/setters
>>>to enforce that the length and width must be equal.  Confirm that
>>>length and width remain locked, and that perimeter() and area() work
>>>correctly.
>>
>>class Rectangle:
>>    def __init__(self,length,width):
>>        self.length=length
>>        self.width=width
>>    def area(self):
>>        return self.length*self.width
>>    def perimeter(self):
>>        return 2*self.length+2*self.width
>>class Square(Rectangle):
>>    def set_side (self):
>>        if self.length!=self.width:
>>           
>	Where's the rest of that -- not to mention you called it "set_side" but
>never pass a side into it for use.
> 
>-=-=-=-=-=-=-=-
>
>class Rectangle(object):
>    def __init__(self, length, width=None):
>        self.length = length
>        if width is None:
>            self.width = length
>        else:
>            self.width = width
>    def area(self):
>        return self.length * self.width
>    def perimeter(self):
>        return 2 * (self.length + self.width)
>
Thanks for posting that.  I had given up on trying it.  I follow the
changes you made up this point.  I will have to think some more to get
the rest of this.
The way you provided a catch for not having a width, I don't
understand the purpose of a Square subclass.  Couldn't side just be
length?
BTW I am willing to forget any mention of getter/setter.  We can just
pretend that never happened.

>class Square(Rectangle):
>    def __init__(self, side):
>        self.side = side
>    def _getLength(self):
>        return self.side
>    def _getWidth(self):
>        return self.side
>    def _setLength(self, vlu):
>        self.side = vlu
>    def _setWidth(self, vlu):
>        self.side = vlu
>    length = property(_getLength, _setLength)
>    width = property(_getWidth, _setWidth)
>
>aRect = Rectangle(2, 4)
>print aRect.length, aRect.width, aRect.area(), aRect.perimeter()
>aRect.length = 9
>print aRect.length, aRect.width, aRect.area(), aRect.perimeter()
>
>
>aSqr = Square(3)
>print aSqr.side, aSqr.length, aSqr.width, aSqr.area(), aSqr.perimeter()
>aSqr.length = 4
>print aSqr.side, aSqr.length, aSqr.width, aSqr.area(), aSqr.perimeter()
>aSqr.width = 5
>print aSqr.side, aSqr.length, aSqr.width, aSqr.area(), aSqr.perimeter()
>aSqr.side = 7
>print aSqr.side, aSqr.length, aSqr.width, aSqr.area(), aSqr.perimeter()
>
>-=-=-=-=-=-=-=-=-
>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>property2.py
>2 4 8 12
>9 4 36 26
>3 3 3 9 12
>4 4 4 16 16
>5 5 5 25 20
>7 7 7 49 28
>
>C:\Users\Wulfraed\Documents\Python Progs>