# [Oberon] How to mimic an associative array

Duke Normandin dukeofperl at ml1.net
Thu Dec 2 05:41:20 CET 2010

```On Thu, 2 Dec 2010, Chris Burrows wrote:

> >-----Original Message-----
> >From: Duke Normandin [mailto:dukeofperl at ml1.net]
> >Sent: Thursday, 2 December 2010 10:18 AM
> >To: Chris Burrows; ETH Oberon and related systems
> >Subject: Re: [Oberon] How to mimic an associative array
> >
> >> "Algorithms and Data Structures" (Oberon Version Aug 2004)
> >by Niklaus Wirth.
> >> You can download a copy (1.2 MB PDF file. 179 pages) from:
> >>
> >
> >I have a copy, and I looked at it this morning. Scary! It's
> >the presentation, NOT the subject matter. If only I wasn't so
> >mathemata-phobic. :D
> >
>
> I just had a closer look myself. I agree that Section 5.4 is scary but I'm
> happy just to take his word for it:
>
> "What we wish to be assured of is that on the average the number of probes
> is small. The following probabilistic argument reveals that it is even very
> small."
>
> (Translation: "Here's proof that it works very efficiently.")
>
> and wait for somebody else to dispute his reasoning ;-)
>
> As for the first three sections, they are very precise and concise but not
> nearly as scary. Reading them is a bit like eating rich food - if you gobble
> it down you'll get indigestion. Consequently, here's a couple of suggestions
> that hopefully that will make it easier to absorb:
>
> 1. Print out the pages - don't attempt to read them off a screen.
>
> 2. Spend as much time reading each sentence as you would normally take to
> read a paragraph in a novel or a newspaper.
>
> Once you have done that, let us know if any particular sentence does not
> make any sense.

All good advise! I wonder though, if we're talking about the same
thing? Somehow implementing a Perl-like associative array, using basic
Oberon-2 data-types? As in: http://en.wikipedia.org/wiki/Hash_table

--
Duke

```