tilly wrote:

Much of what you've just said for multi-method dispatch by type works perfectly well already in Perl if you're dispatching by class using OO. Arguing for how great multi-method dispatch would be using examples where OO dispatch suffices is not going to convince me.

I'm not sure I follow you here. Are you suggesting that in examples like I provided, the invocants be in different classes? Whenever possible, I really like to minimize the number of classes and creating a new class just to handle a different argument type to a method frequently does not make sense. One example of this would be the constructor:

my $parser1 = Some::Parser->new($string);
my $parser2 = Some::Parser->new($uri_object);
my $parser3 = Some::Parser->new($fh_object);

[download]

In that example, with three constructors, each taking a different argument type, we can still return objects in the same class. Class-based dispatching wouldn't make sense there. Did I misunderstand what you were saying?

Dan Sugalski points to event driven code where different objects generate events and your event handlers are a series of methods whose arguments are the objects generating the events. I shouldn't push the event handling into the objects themselves because they shouldn't care how they're going to be used. Instead, I have a simple GUI class which knows that it's supposed to handle events. This is a common Java idiom and it works very well.

The main problem I have with MMD is I am frequently more interested in the interface an object provides rather than its type/class.

Oh, and you'll see that I'm not the one who used the getter/setter example. While it's a reasonable example that fits well with many people's coding styles, I also prefer different names there because the methods are doing different things. When the methods are conceptually doing the same thing, they should have the same name, if possible.

Update: Whoops! I guess I did use a getter/setter example :)

Cheers,
Ovid

New address of my CGI Course.

In reply to Re^2: The beauty of MMD by Ovid
in thread Perl 5's greatest limitation is...? by BrowserUk

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.