[Info-vax] Error Messages in Basic - %BASIC-E-PARMODNOT, mode for parameter <n> of routine <procedure-name> not as declared

[Dave Froble]

On 6/9/2019 10:57 AM, Scott Dorsey wrote:
> Dave Froble  <davef at tsoft-inc.com> wrote:
>>
>> I guess when one programs in a language that forces variable
>> definitions, then one might feel that it's a "good practice".
>
> It is not just good practice, it is critical.  I strongly suggest you read
> Djikstra on the subject.

Did that, long ago.  He ain't a god.  More than one side to just about 
every issue.  Good practice, I'll give you.  Critical, no.  A bit too 
rigid for me.

>> Interesting that so many in c.o.v express their way as being the only way.
>
> I started to program back in the era before variable definitions, when
> you could accidentally typo a period for a comma and wind up with spurious
> variables appearing in your program instead of syntax errors.  I spent a
> -lot- of time trying to find bugs that would have been detected easily by
> the good practice of defining everything explicitly.

Yes, that works.  But not doing so can work also.

> I understand that in 1966 it seemed like a good idea but it turned out not
> to be.  We lost a Mariner spacecraft because of it.

I didn't lose a Mariner spacecraft ....

>>> the compiler will not let you substitute one for the other even though
>>> both occupy 64-bits. So if you find yourself needing to covert between
>>> the two, use a variant record as seen here:
>>
>> But, yes, I now understand that it's not a problem with the 8 bytes of
>> data, it's a problem with the compiler thinking that it's the wrong type
>> of data.
>
> Right, it is that it is defined to one thing, while the contents are another
> thing.

And in this specific case, I might not have had that problem.  Maybe. 
Contrary to what I sometimes write, I do use a lot of explicit declarations.

:-)

-- 
David Froble                       Tel: 724-529-0450
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