You're mixing terms. A 71-sided polygon isn't a parallelogram, so to discard it because it doesn't have rotational symmetry is a straw man.

There are a set of properties that all polygons have (closed, etc), and a set of properties that all regular polygons have (regular angles, sides of the same length, and rotational symmetry at least 360/n degrees around the center, where n is the number of sides). This seems to lend itself to an inheritance tree, but, like the fibonacci sequence, the first approach isn't appropriate.

Instead, the more appropriate approach would seem to be to elaborate the rules that arise based on the properties of the object, not the class, and to (potentially) precalculate those results on object creation (with appropriate caching). For example, a square has certain properties. So, when an object of the ClosedShape class is instantiated that matches the properties of a square, the appropriate results would be calculated. But, it's still of the ClosedShape class.

I think that this would start to solve the generic and specific problems you have flyingmoose have raised.

------
We are the carpenters and bricklayers of the Information Age.

Please remember that I'm crufty and crochety. All opinions are purely mine and all code is untested, unless otherwise specified.

In reply to Shapes don't need inheritance by dragonchild
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.