Re: [Gm2] Fwd: CASE: gm2-4.1.2 of 2011-11-08 bug (or possibly philosophical difference)

[john o goyo]

> Sorry, but I do not quite get what you mean by missing value. Do you mean that 
> one item of Choice,
> i.e. weight, is not used by the CASE record? If yes, then it is clear 
to me what gm2 should do, not
>  enforce that all values are covered if PIM is specified. E.g.
> ItemType = RECORD CASE : INTEGER OF
> 1: ....
> 2: ....
>      END(*CASE*); END(*RECORD*)
>
> should be allowed and the compiler must not require to list all integer 
> numbers. Similarly when
> Choice enumerates a finite set of cases the compiler must not require 
to list all elements
> of the enumeration type.
>

This is precisely what I meant.  My apologies for being so obscure.

john


> Regards,
> Andreas
>
>
> ETH Zurich
> Prof. Dr. Andreas Fischlin
> Systems Ecology - Institute of Integrative Biology
> CHN E 21.1
> Universitaetstrasse 16
> 8092 Zurich
> SWITZERLAND
>
> address@hidden<mailto:address@hidden>
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>
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>              Make it as simple as possible, but distrust it!
> ________________________________________________________________________
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>
>
> On 10/11/2011, at 22:43 , john o goyo wrote:
>
> As we all know, PIM allows missing values in CASE statements but ISO does not.  
> At present, gm2 enforces the ISO restriction regardless of which PIM is 
> specified.  (A simple example may be found below.)
>
> What should gm2 do?  (The problem arises, of course, in compiling existing 
> code.)
>
> john
>
> ==============================
> MODULE Test;
>
> TYPE
> Choice = (colour, size, weight);
> ItemType = RECORD
>        CASE c :Choice OF
>          colour: col :CHAR;
>         |size:   s :CARDINAL;
>        (*
>         * PIM allows missing values but ISO does not.
>         *)
>        END (*CASE*);
> END (*ItemType*);
>
> VAR
> item :ItemType;
>
> BEGIN
> item.col := 'R';
> END Test.
> ==============================