[Oberon] Re (n): syntax in BB, CP, GPCP and V4 ...
Dieter
d.gloetzel at web.de
Tue Jul 25 10:00:51 CEST 2017
Just to remind you, that there exists a nice prettyprinter written by G.
Feldmann, running on ETHOberon Windows plugin.
Regards,
Dieter
Am 25.07.2017 um 01:44 schrieb Hans Klaver:
> Jörg wrote:
>
>> Indentation is indeed a totally personal thing.
>
> It is interesting to catalogue the different indentation styles used
> by some well known (and less well known) programmers of Oberon and
> Component Pascal source code. With one of the exercises of the Reiser
> & Wirth book as material I wrote out various indentation styles.
>
> Crudely four styles of indentation can be discerned:
> - No indentation (Daniel)
> - Minimal indentation (Reiser / Mössenböck); the difference between
> the two is in the indentation of declarations (e.g. VAR) at the
> procedure level
> - Classical indentation (Wirth & Gutknecht); has the most consistent
> indentation of scope levels.
> - Knuth indentation (Knuth / Campbell); also quite consistent, but
> rather convoluted.
>
>
> MODULE M; (* After Exercise 6.4 (p. 85) from Reiser & Wirth,
> Programming in Oberon *)
> IMPORT Out;
> VAR i, j: INTEGER;
> PROCEDURE A*;
> VAR i: INTEGER;
> PROCEDURE B(VAR i, j: INTEGER);
> VAR k: INTEGER;
> BEGIN k := i; i := j; j := k END B;
> BEGIN i := 2; B(i, j)
> END A;
> PROCEDURE C*;
> BEGIN A; i := 2*j;
> Out.Int(i, 5); Out.Int(j, 5); Out.Ln
> END C;
> BEGIN
> END M.C
>
> (**************************************)
>
> MODULE M; (* Daniel, http://www.waltzballs.org/other/prog.html#track *)
> IMPORT Out;
> VAR i,j:INTEGER;
>
> PROCEDURE A*;
> VAR i:INTEGER;
>
> PROCEDURE B(VAR i,j:INTEGER);
> VAR k:INTEGER;
> BEGIN k:=i;i:=j;j:=kEND B;
>
> BEGIN i:=2;B(i,j)
> END A;
>
> PROCEDURE C*;
> BEGIN A;i:=2*j;
> Out.Int(i,5);Out.Int(j,5);Out.Ln
> END C;
>
> BEGIN
> END M.C
>
> (**************************************)
>
> MODULE M; (* M. Reiser, The Oberon System
> and M. Reiser & N. Wirth, Programming in Oberon *)
> IMPORT Out;
> VAR i, j: INTEGER;
>
> PROCEDURE A*;
> VAR i: INTEGER;
>
> PROCEDURE B(VAR i, j: INTEGER);
> VAR k: INTEGER;
> BEGIN
> k := i; i := j; j := k
> END B;
>
> BEGIN
> i := 2; B(i, j)
> END A;
>
> PROCEDURE C*;
> BEGIN
> A; i := 2*j;
> Out.Int(i, 5); Out.Int(j, 5); Out.Ln
> END C;
>
> BEGIN
> END M.C
>
> (*************************************)
>
> MODULE M; (* H. Mössenböck, Object Oriented Programming in Oberon-2 *)
> IMPORT Out;
> VAR i, j: INTEGER;
>
> PROCEDURE A*;
> VAR i: INTEGER;
>
> PROCEDURE B(VAR i, j: INTEGER);
> VAR k: INTEGER;
> BEGIN
> k := i; i := j; j := k
> END B;
>
> BEGIN
> i := 2; B(i, j)
> END A;
>
> PROCEDURE C*;
> BEGIN
> A; i := 2*j;
> Out.Int(i, 5); Out.Int(j, 5); Out.Ln
> END C;
>
> BEGIN
> END M.C
>
> (**************************************)
>
> MODULE M; (* Wirth & Gutknecht, Project Oberon *)
> IMPORT Out;
> VAR i, j: INTEGER;
>
> PROCEDURE A*;
> VAR i: INTEGER;
>
> PROCEDURE B(VAR i, j: INTEGER);
> VAR k: INTEGER;
> BEGIN
> k := i; i := j; j := k
> END B;
>
> BEGIN
> i := 2; B(i, j)
> END A;
>
> PROCEDURE C*;
> BEGIN
> A; i := 2*j;
> Out.Int(i, 5); Out.Int(j, 5); Out.Ln
> END C;
>
> BEGIN
> END M.C
>
> (**************************************)
>
> MODULE M; (* Knuth. E.g. see: http://brokestream.com/tex.pdf *)
> IMPORT Out;
> VAR i, j: INTEGER;
>
> PROCEDURE A*;
> VAR i: INTEGER;
>
> PROCEDURE B(VAR i, j: INTEGER);
> VAR k: INTEGER;
> BEGIN k := i; i := j; j := k
> END B;
>
> BEGIN i := 2; B(i, j)
> END A;
>
> PROCEDURE C*;
> BEGIN A; i := 2*j;
> Out.Int(i, 5); Out.Int(j, 5); Out.Ln
> END C;
>
> BEGIN
> END M.C
>
> (**************************************)
>
> MODULE M; (* R. Campbell, Subsystem Lib for BlackBox Component
> Framework,
> see the Component Pascal Collection, http://www.zinnamturm.eu/ *)
> IMPORT Out;
> VAR
> i, j : INTEGER;
>
> PROCEDURE A*;
> VAR
> i : INTEGER;
>
> PROCEDURE B(VAR i, j : INTEGER);
> VAR
> k : INTEGER;
> BEGIN
> k := i; i := j; j := k
> END B;
>
> BEGIN
> i := 2;
> B(i, j)
> END A;
>
> PROCEDURE C*;
> BEGIN
> A;
> i := 2*j;
> Out.Int(i, 5); Out.Int(j, 5); Out.Ln
> END C;
>
> BEGIN
> END M.C
>
>
> Anyone can choose his or her favourite indentation style.
>
> I personally don't like the two extremes (Daniel and Knuth /
> Campbell). Imho they don't follow Einstein's criterium "Make it as
> simple as ...": Daniel's is too simplistic and Knuth's / Campbell's
> are too convoluted.
>
> The classic Wirth / Gutknecht style is the only style that is
> completely consistent: every scope has its own indentation.
> BlackBox uses this style as standard. See:
> https://hansklav.home.xs4all.nl/ProgrammingConventionsBB.pdf
>
> Some might find the Reiser / Mössenböck styles more aesthetically
> pleasing because of their simplicity. Although these styles are not as
> consistent as the Wirth / Gutknecht style, in practice this doesn't
> matter much because there is only one module scope per compilation
> unit, and nested procedures are rarely used in Oberon programs.
>
> The latter styles are used in two excellent books: /The Oberon
> System/ by Martin Reiser and /Object-Oriented Programming in
> Oberon-2/ by Hanspeter Mössenböck. These books are the two best
> typeset Oberon books there are (imho). Unfortunately both have long
> been out of print. A scanned copy of /The Oberon System/ can be found
> on the internet here:
> http://oberoncore.ru/library/reiser_the_oberon_system_user_guide_and_programmers_manual ,
> and there's a pdf-version of /OOP in Oberon-2/ here:
> http://ssw.jku.at/Research/Books/Oberon2.pdf . In this pdf the source
> code indentation is not rendered entirely accurately, so also have
> look at a scanned version of this book:
> https://books.google.nl/books?id=BseoCAAAQBAJ&printsec=frontcover&dq=object+oriented+programming+in+oberon-2&hl=nl&sa=X&redir_esc=y#v=onepage&q=object%20oriented%20programming%20in%20oberon-2&f=false
>
> --
> Hans Klaver
>
>
>
>
>
>
>
> --
> Oberon at lists.inf.ethz.ch mailing list for ETH Oberon and related systems
> https://lists.inf.ethz.ch/mailman/listinfo/oberon
--
____________________________________
Dr. Dieter Glötzel
Im Rosengarten 27
64367 Mühltal
Tel.: 06151 / 360 82 72
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