[Oberon] Texts

[peter at easthope.ca]

From:	Treutwein Bernhard <Bernhard.Treutwein at Verwaltung.Uni-Muenchen.DE>
Date:	Mon, 30 Apr 2018 08:53:35 +0000
> hmm, the original format is well documeted in Wirth's Project Oberon
> both in the original 1992 Edition (which is available with some edits 
> here: https://www.inf.ethz.ch/personal/wirth/ProjectOberon1992.pdf)
> and in the 2013 Edition. In both editions it is Chapter 5.

Yes, I have it, thanks.  That ProjectOberon1992.pdf is in reality a 
2005 edition. The title page has "Edition 2005".  Although the 
differences 1992 => 2005 probably don't have a large impact on this 
discussion.

> Of course there were extensions later and I do not know, if and which 
> of these are documented in the original Project Oberon, ...

You meant extensions of functionality?  I meant extensions of records such 
as "TextDesc* = RECORD (Objects.ObjDesc)".  

Project Oberon, Edition 2005, page 79 has this.

Text = POINTER TO TextDesc;
TextDesc = RECORD
  len: LONGINT;
  notify: Notifier
END;

My original message referred to Text in S3 and the Oberon subsystem of A2. 

Text* = POINTER TO TextDesc;
TextDesc* = RECORD (Objects.ObjDesc)
  len*: LONGINT;	(** Text consists of characters 0 to T.len - 1. *)
  obs: Objects.Library;	(* Library containing objects located in text. *)
  trailer: Piece;
  org: LONGINT; (*cache*)
  pce: Piece
END;

These definitions are similar to the extent that both define Text. 
Beyond that quite different.  Pieter Muller might have explained the 
motivation for the Object based definition in his thesis.  Tips 
welcome of course.  When there is time I can add the "Word" example 
for the earlier definition of Text.

I didn't intend to start another flame war.  Rather I'm trying to make 
some documentation helpful to novice J. Doe.  Also to improve my own 
understanding.

Thanks,                         ... Lyall E.








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