From: Pit Capitain <pit@...>
Date: 2002-09-30T07:20:19+09:00
Subject: Re: thoughts on typelessness

On 29 Sep 2002, at 12:09, dblack@candle.superlink.net wrote:

> (lots of interesting remarks about explicit typing discussion)
> 
> One possible factor, I think, is the #type method.  As I mentioned on
> IRC this evening, I sometimes wish Ruby didn't have it.  It's harder
> to make the argument that objects don't have types, when the objects
> themselves willingly tell you their types.... :-)  And I might add
> #is_a? and #kind_of? to the list.  Maybe they're necessary for
> reflection.  It's interesting to try to program without them.
> 
> (snip)
> 
> I've done that, for instance, in my dbdbd (database definer) program.
> It uses 1-originating array notation to index columns, but can also
> use field-names.  So the reader method for the sort_key (for example)
> is:
> 
>    def sort_key
>      @sort_key - 1
>    rescue NameError
>      @sort_key
>    end

When you announced dbdbd I quickly browsed through the code. I 
had the impression that I understood your well written program - 
besides this very example. I really tried to understand what's going 
on, but I just couldn't get it.

> which I think looks better than:
> 
>    def sort_key
>      if @sort_key.respond_to?(:-)
>        @sort_key - 1
>      else
>        @sort_key
>      end
>    end

Ok. With this alternative code and the remarks in your mail I finally 
understand what you did. But for me the most intention revealing 
implementation would simply be:

  def sort_key
    if @sort_key.is_a? Integer
      @sort_key - 1
    else
      @sort_key
    end
  end

I'm sure it would be very interesting to try to program without #type, 
#is_a? etc and I'm sure I will try to do so in the future, but for me 
this wasn't a good example. If you think so, too, maybe you could 
find an other implementation. I'd be very interested in what you'd 
come up with.

Regards,
Pit