[Oberon] Procedure variables and local procedures

[Chris Burrows]

> -----Original Message-----
> From: chris [mailto:chris at gcjd.org]
> Sent: Sunday, 1 October 2017 3:20 AM
> To: chris at cfbsoftware.com; ETH Oberon and related systems
> Subject: Re: [Oberon] Procedure variables and local procedures
> 
> On Sat, 30 Sep 2017 21:25:48 +0930, Chris Burrows wrote:
> > Oberon-07 is the replacement of the Oberon language (1990) as
> designed
> > by Prof Wirth NOT the language Oberon-2 (1995) which was designed
> by
> > Hanspeter Mossenbock (originally called Object Oberon).
> 
> Just a historical remark: Object Oberon (June 1989) is quite
> different from Oberon-2. While both attempt to add type bound
> procedures, Object Oberon uses explicit classes with included
> procedures a bit similar to Active Oberon in style and has features
> for explicit message sending and receiving.
> 
> Oberon-2 earliest report I know is from 1993 by H. Mössenböck and N.
> Wirth.
> 

I stand corrected. 1995 is the date of the latest revision of the Oberon-2
report that I have.

Just another historical remark:

H. Mössenböck states in the preface to his book 'Object-Oriented Programming
in Oberon-2' (also dated 1993):

"The design of Oberon reflects the experience of the man who developed Algol
W, Pascal and Modula-2. In Oberon-2, **the author of this book** added
several extensions to the Oberon language that make it more suitable for
object-oriented programming."  

(** My emphasis)

I believe that paragraph leads to a better understanding of the fact that
Oberon-07 (by Wirth) is not Oberon-2- or whatever successor of Oberon-2 some
might think it to be.

> My main interest was to learn about the motivation of the omission or
> absence of the language features from Oberon-07 that were available
> in earlier versions of Oberon.
>

If you were thinking of Oberon-2 when you said earlier versions of Oberon I
can understand some of your previous questions. If 

a) you accept that Oberon-07 is a successor to Oberon, not Oberon-2, and 

b) you have read the document "Differences between Oberon-07 and Oberon"
which you can download from:

https://www.inf.ethz.ch/personal/wirth/Oberon

does that answer your questions?

Regards,
Chris Burrows
CFB Software
http://www.astrobe.com