From: "Thies C.  Arntzen" <thieso@...>
Date: 2006-08-13T03:35:13+09:00
Subject: Re: PATCH to make internal Hash class retain order...

Brian McCallister schrieb:

> On Aug 12, 2006, at 9:55 AM, Thies C. Arntzen wrote:
>
> > Hi there -
> >
> > beeing new to ruby (thru rails) and coming from a strong php
> > background
>
> <snip />
>
> > * remember the order in which elements have been added to a Hash (at
> > the cost of 2 extra pointers in every hash-bucket + 2 extra pointers
> > per hash-table)
> > * use this order for iterating (st_foreach will use this order)
> > * implement a call Hash.order! allows the user to change the internal
> > order;-)
>
> Nice :-) The better place for discussion hacking on the ruby
> interpreter itself is probably ruby-core.

i wasn't aware of that list;-) subscribed...

>
> How difficult would it be to do an OrderedHash data structure as a C
> extension instead of in Ruby?

i really believe that it needs to be a 1st class citizen - the reason
it's done in C is because userland imposes too much overhead (i
believe) and converting forward<->back to the normal Hash would be
slow, memory intensive and ordering information would get lost on the
way...

also the amount of code added to the Hash class is ~20 lines of C-code
- this code adds zero overhead. the bigger chunk of the code was added
to the st.c which is the underlying library for handling hash-tables -
and duplicating > 600 lines of code to add ~60 lines didn't seem very
cool to me;-)

best, thies