Wirth's PIM4 ISBN-0-387-50150-9 : Where is ConstantDeclaration?

[trijezdci]

I am looking at Wirth's "Programming in Modula-2", 4th Edition with ISBN-0-387-50150-9, Appendix 4, page 171ff and I simply cannot find the diagram for ConstantDeclaration.

I have gone over all the diagrams several times, forwards and backwards, and I simply cannot find the one for ConstantDeclaration which is referenced in the diagrams for Definition and Declaration.

Is it just me, have I gone blind, or is this missing from the book?

Can folks here verify this with their copies of PIM4 please?

thanks in advance

[Christoph Schlegel]

Post by trijezdci
I am looking at Wirth's "Programming in Modula-2", 4th Edition with ISBN-0-387-50150-9, Appendix 4, page 171ff and I simply cannot find the diagram for ConstantDeclaration.
I have gone over all the diagrams several times, forwards and backwards, and I simply cannot find the one for ConstantDeclaration which is referenced in the diagrams for Definition and Declaration.
Is it just me, have I gone blind, or is this missing from the book?
Can folks here verify this with their copies of PIM4 please?
thanks in advance

I didn't know we don't have to declare constants or - even more interesting - there simply are no const declarations...

Joking aside, my version of PIM4 is in german language, ISBN 3-540-51689-1 (and there are 5 more ISBN numbers in the book which I don't write down here unless anyone wants to know more) and you are right, there is no ConstantDeclaration in Appendix 4. Of course there is Appendix 1 where you find line 12:

ConstantDeclaration = ident " = " ConstExpression .

Guess you found an accidental omission -

Regards,

Christoph

[Christoph Schlegel]

Post by Christoph Schlegel

Post by trijezdci
I am looking at Wirth's "Programming in Modula-2", 4th Edition with ISBN-0-387-50150-9, Appendix 4, page 171ff and I simply cannot find the diagram for ConstantDeclaration.
I have gone over all the diagrams several times, forwards and backwards, and I simply cannot find the one for ConstantDeclaration which is referenced in the diagrams for Definition and Declaration.
Is it just me, have I gone blind, or is this missing from the book?
Can folks here verify this with their copies of PIM4 please?
thanks in advance

I didn't know we don't have to declare constants or - even more interesting - there simply are no const declarations...
ConstantDeclaration = ident " = " ConstExpression .
Guess you found an accidental omission -
Regards,
Christoph

In chapter 8 about declaration of constants and variables Wirth logically defines ConstantDeclaration right before ConstExpression. My version of PIM4 has the diagram of "string" before ConstExpression. Yes, it is missing in App4.

[Nemo]

Post by Christoph Schlegel
Guess you found an accidental omission -

Indeed. Railroad diagrammes were introduced in PIM3, which is also
missing ConstantDeclaration.

[trijezdci]

Post by Nemo

Post by Christoph Schlegel
Guess you found an accidental omission -

Indeed. Railroad diagrammes were introduced in PIM3, which is also
missing ConstantDeclaration.

Not the first time that I found something "accidental", but never mind.

Meanwhile, I have generated diagrams for PIM4 and put them on a page at:

http://modula-2.info/m2pim/pmwiki.php/SyntaxDiagrams/PIM4NonTerminals

Speaking of accidents, the diagram for Variant seemed wrong to me when I created it. It has a bypass which permits Variant to be empty. Not only is it bad practise to have empty productions in a grammar, but it is also nonsensical, allowing any number of occurrences of | in a variant field list.

But I checked the diagram in the annex of the book and it clearly has that bypass. I didn't check then against the EBNF, but now that I look at the result, I did and the EBNF does not permit Variant to be empty, so the diagram in the annex is wrong. I will fix the diagram on the wiki later. Naturally, I can't fix it in the book, but Springer have only recently re-released the book, I bet they still have the errors in there. I guess I should write them a mail.