Once you decide to use @ISA, you limit choices on how to model things. Your implementation of a Square has to be the same as your implementation of a Parallelogram. Which is an inconvenient implementation of a Square.
Why does the implementation of a square to be the same as one of a parallologram? That's not why how one typically uses inheritance. An implementation of a base class is different than one of a super class - otherwise, there would not be a point in using inheritance. A base class and a super class typically share part of their implementation - and sometimes everything of a super class is inherited by a base class; that is, the base class doesn't redefine any method, or mask any attribute, of the super class.

As for a parallelogram being inconvenient as an implementation of a square, I'm kind of flabbergasted. I cannot think of any property a parallelogram has, that a square hasn't.

Abigail

In reply to Re: inheritance and object creation by Abigail-II
in thread inheritance and object creation by knew

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.