From: Marek Janukowicz <childNOSPAM@...17.ds.pwr.wroc.pl>
Date: 2004-05-20T00:18:47+09:00
Subject: Re: How to duck type? - the psychology of static typing in Ruby

On Tue, 18 May 2004 11:20:30 +0200, Robert Klemme wrote:
>> In other words, this feature would be equivalent of 'strongtyping'
>> library, just with better syntax and compile-time checking (to avoid
>> runtime overhead).
>
> But there's a whole lot of problems waiting:
>
>  - You need return type declarations (at least optional)

You're right.

>  - What do you do if you invoke a method with a required parameter type bu
> t your value resides in some typeless var?

Good point - that's the question I didn't reconsider.

>  - You'll likely and up casting values all the time => errors here can
> only be detected at runtime

You may be right here too :)

>  - Internal handling of references must be completele changed.

I do not (yet) think about consequences for Ruby interpreter.

>  - What do you gain by type info if any instance is free to override
> methods defined in the class at will?

How often do your instances override methods defined in class? You're
right - type info would not help in this case, but most programs do not
do this.

> Although I can see the benefit for some users, I'm still not convinced
> that this is a good idea, that it fits Ruby well and / or that this will
> show up in Ruby in the near future.  

I'm not convinced too - that why I am presenting my idea here. Thanks
very much for your thoughts - they gave me much broader view of the
whole problem.

-- 
Marek Janukowicz