First, I called him "Ben" without thinking about it. He happens to be a friend of mine, we talk on the phone and calling him Ben seems to be natural. It wasn't intended as making thing "personal."

As for the rest of your points, argue them with Dan Sugalski :) Incidentally, that link points to a concrete example of something that might satisfy tilly's desire to see a problem for which MMD is suitable.

Oopsie. The code silently fails.

That is an argument for prototypes on methods, not for MMD specifically.

As I pointed out earlier in my post, my discussion was about both MMD and proper argument handling. To my mind, you can't have the former without the latter. And I agree with your concerns about B&D. I, too, don't like B&D, but to my point of view, properly implemented MMD could let me having sanity checking without forcing any sort of B&D. See Perl 6's ideas behind MMD for examples.

Jumping into a fray that isn't mine:

I think that the point is MMD is usefull and would be nice to have. I'm not sure what your argument agianst that was except that you didn't like his argument. So here is a plain as day example using Perl6 MMD and i'd like to see your example of the same code that is at least as simple.

multi method name ()              { return $.name };
multi method name (Str $new_name) { $.name = $new_name; $new_name };
[download]

The return value of the second call is always debatable, but not realy the point here. This is obviously a very simple example, but the point is, anytime your action varies depending on the types of paramters, MMD is a nice trick to have available. BTW Perl6 allows MMD and allows you to still have your old fashion perl5 send me everything in @_ subs too, so you can have your cake and eat it too (whatever that means ;) )

Here is a Perl 5 example that is simpler than what you provided, even without the Perl 6 syntactic sugar:

sub get_name {$_[0]{name}}
sub set_name {$_[0]{name} = $_[1]}
[download]

And in Ruby it is simpler still:

attr_accessor :name; # creates name and name= methods for you
[download]

The one thing that my examples are missing which yours provides is a check that the accessor really wants a string. This check is not something that I personally value, but YMMV.

If you change the problem then yes that is an answer. The point of MMD is one name for a sub that acts differently based upon inputs. The original question was over perl 5 being limited by not having MMD. Which it can be made to do, but your post does not. You may claim that MMD is useless to you, and that is fine, however it makes some tasks quite simple like shown in my post. Your answer is fine and it is probably arguable that any use of MMD can be reformated so that it can be solved without MMD. The same is true for OO, and probably any other single peice of programming or concept, it is however not realy a sound argument agianst anything at all.


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Eric Hodges

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