From: Meino Christian Cramer <Meino.Cramer@...>
Date: 2003-09-13T19:56:41+09:00
Subject: Re: Duck Typing

From: Dan Doel <djd15@po.cwru.edu>
Subject: Re: Duck Typing
Date: Sat, 13 Sep 2003 18:57:25 +0900


> You really shouldn't use #is_a? or #respond_to? much at all. That's not what
> duck typing is about.
> 
> Just write your method to use methods that the passed in object should 
> have, by
> the contract of the method.  Then test to make sure your program works.
> 
> Excessively using #is_a? and #respond_to? is essentially trying to turn ruby
> from a dynamically typed language into an ad-hoc statically typed language,
> which isn't in the spirit of duck typing at all.
> 
> The only real reason you should be using these methods is if you need to
> take different actions depending on which of several methods is available.
> If you're just checking whether the only method you use exists or not, 
> you're
> just doing extra work most of the time.  The interpreter will tell you if it
> isn't there.
> 
> It can be a confusing issue if you haven't read the discussions before. 
> There
> was a big one some weeks back, so it might be worth it to read the ruby-talk
> archives to clear some stuff up without duplicating all of it again.
> 
> Cheers.
> 
> - Dan
> 
> 
> 

Thanks for your reply, Dan...will go to the archives !

Kind regards,
Meino