Re: [ooc-compiler] FOR Loops And Structured Variables

[August K. <fus...@co...>]

Frank Copeland wrote:
> August Karlstrom wrote:
> 
>> Why doesn't the following module compile?
>>
>>    MODULE Test;
>>       VAR a: ARRAY 1 OF LONGINT;
>>    BEGIN
>>       FOR a[0] := 0 TO 1 DO END
>>    END Test.
>>
>> I've read that in Modula, loop variables in FOR loops cannot come from 
>> structured variables, but I can't find that restriction in the 
>> Oberon-2 report. Anyway, what's the motivation for the restriction?
> 
> 
>  From the Oberon-2 Report:
> 
>     ForStatement = FOR ident ":=" Expression TO Expression
>                    [BY ConstExpression] DO StatementSequence END.
> 
> and 'ident' is defined as:
> 
>   1. Identifiers are sequences of letters and digits. The first character
>   must be a letter.
> 
>     ident = letter {letter | digit}.
> 
>   Examples:     x     Scan     Oberon2     GetSymbol     firstLetter
> 
> This obviously excludes structured variables as loop variables.

Yes of course, thanks.

> Motivation? You would have to ask Wirth or Gutnecht about that, but my 
> guess would be disbelief that anyone sensible would use anything other 
> than a simple integer variable as a loop variable.

OK.


Thanks,

August