From: Michael Fellinger <m.fellinger@...>
Date: 2006-07-24T12:12:52+09:00
Subject: Re: I'll have the duck!

On Monday 24 July 2006 11:40, John Carter wrote:
> duck == mixin
>
> Consider the Enumerable mixin.
>

Well... i don't think mixins are exactly that :)
what trans proposes is more like excessive duck-typing

imagine a duck
you can make it quack
and you know - what the duck quacks can be processes in many ways...

Duck.quack.record.to_tape.copy.to_cd.send_to producer

might be a bit excessive, but in essential that's it...
i've learned that kind of 'method' in Dylan, where you define that stuff a bit 
different - you have a kind of reversed dispatcher that adds classes to 
methods and decides which method to use given what object you operate on.

little syntax help - the stuff in <> are classes, <duck> and <fish> are 
subclasses of <animal>

########################################

define method to-s (animal :: <animal>)
� color(animal)
end

define method color (duck :: <duck>)
� "brown"
end

define method color (fish :: <fish>)
� "grey"
end

########################################

the methods are not added to the object - they look like that afterwards:
(using ruby for that, so it looks a bit nicer ;)

def color (x)
� if x === Animal
� � if x === Fish
� � � "grey"
� � elsif x === Duck
� � � "brown"
� � end
� end
end �


don't want to hang around in dylan for too long, but this was a new way (at 
least for me) to express methods...
now, this could be driven further

you could attach methods to objects that respond to specific methods

########################################

methods to_a
� def compact
� � delete_if{|e| e.nil? }
� end

� def sum
� � inject{|s,v| s+v}
� end
end

class Foo
� def to_a
� � [1,2,3,nil]
� end
end

Foo.new.compact.sum
# 6

########################################

something like that...
i find that is true ducktyping :)
however... the beauty is in the eye of the beholder, so it might look 
butt-ugly to someone else :|

i just kinda like the idea itself - the implementation in ruby would be 
enormous work (as i imagine it at least) - and would slow down ruby 
further...

these assumptions are just in my honest opinion :) might as well be pretty 
neat to integrate and work with... but i have my doubts...

>
>
> John Carter                             Phone : (64)(3) 358 6639
> Tait Electronics                        Fax   : (64)(3) 359 4632
> PO Box 1645 Christchurch                Email : john.carter@tait.co.nz
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>
> Carter's Clarification of Murphy's Law.
>
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> later."
>
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