From: Tom Sawyer <transami@...>
Date: 2002-08-04T08:47:35+09:00
Subject: Re: Assoc Class (Hash Pairs)

i recall having a need for it some time ago, but i don't recall off hand
what that was. but the use i recently ran across was for building
complex hierachies (for gui models) where sometimes you have a "child"
object and some times you don't:

complex_hierarchy = [ parent => child,
                      childless,
                      another_parent => [ subchildless,
                                          subparent => subchild ]
                    ]

                                          
without this, you either have to use hashes with extraneous nils, or
fall back to pure associative arrays.

in effect, i think i may be getting at a merger of hash and array, where
elements can have index => value associations, but others don't.

so that's my need. but the idea of associations in and of themselves
strikes me as if they may be useful on their own.

~transami


On Sat, 2002-08-03 at 16:19, Harry Ohlsen wrote:
> On Sun, 4 Aug 2002 04:05, you wrote:
> > i've been thinking about posting this as an RCR.
> >
> > i would really like to see hash pairs (associations) become real
> > objects. i think it would be a very powerful and useful construct. there
> > are number of things one could then do. The simpliest obviosuly being:
> >
> >   x = 'a'=>1
> >   y = 'b'=>2
> >
> >   hash = { x, y }
> >
> > ordered hashes also become a snap, implemented as arrays of these
> > associations:
> >
> >   ordhash = [ x, y ]
> >
> > or, without the above x and y assignments, just
> >
> >   ordhash = [ 'a'=>1 , 'b'=>2 ]
> >
> > this association class (Assoc?) would of course mixin the comparable
> > module.
> 
> This piques my interest, but I'm at a loss to see what one would DO with one 
> of these.  Ie, you obviously see that some types of problems would be made 
> easier/cleaner by the use of this kind of data structure.
> 
> Can you give an example where having these would be helpful?
> 
> 
-- 
~transami