From: dblack@...
Date: 2006-07-26T21:43:38+09:00
Subject: Re: I'll have the duck!

Hi --

On Wed, 26 Jul 2006, ara.t.howard@noaa.gov wrote:

> On Wed, 26 Jul 2006 dblack@wobblini.net wrote:
>
>> I've always felt that the Achilles' heel of the duck typing metaphor was 
>> the
>> "then it *is a* duck" -- which implies that there's a Duck thing out there
>> which something else can "be".
>
> i was thinking about this on my ride home and recalled a term used in damian
> conway's object oriented perl book (a fastastic book on oo programming btw.)
> and a term he used way back then : 'interface polymorphism.'  the more i
> thought about it the more i like the term better than 'duck typing' because
> it's closer in spirit to the idea of something being an acceptable object
> merely by implimenting (via method_missing or whatever) a certain set of
> behvaiours.

It sounds like a very useful term, but maybe not a synonym for duck
typing...?  I'm not sure, but it doesn't sound like one would say:
Interface polymorphism is a way of thinking about programming in Ruby
[if I'm paraphrasing Dave Thomas correctly].  One might say: Ruby
offers interface polymorphism, which encourages duck typing [if I'm
using i.p. correctly :-]

My view is that we don't need to choose a winner-take-all term to
refer collectively to *everything* connected with Ruby's type
mechanism, including the way(s) programmers use that mechanism.  We
can have a slightly whimsical but expressive term like "duck typing"
to refer to one aspect of it, and other terms to refer to other,
related things.  I'm fond of "duck typing", "quasi-prototyped
objects", and various other terms -- all of which refer to something
of interest.


David

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