[fpc-devel] Dangerous optimization in CASE..OF

[DaWorm]

I store record data in files with a checksum (usually a CRC). I block read
them into an array buffer and verify the checksum.  If it passes, I assign
via typecast the array buffer to a variable of the record type.  If I'm the
only one reading and writing the files that is usually enough to handle
drive bit rot, or transfer errors.

If someone else's code can write the data I validate everything either when
reading and assigning to the record type, or occasionally before use.  Sure
its slow but it's the only safe thing to do. I wouldn't think of abrogating
that responsibility to the compiler.

Jeff

On Jul 2, 2017 4:50 PM, "Marco van de Voort" <marcov at stack.nl> wrote:

> In our previous episode, Florian Kl?mpfl said:
> [ Charset UTF-8 unsupported, converting... ]
> > Am 02.07.2017 um 21:40 schrieb Martok:
> > > Honestly, I still don't understand why we're even having this
> discussion.
> >
> > Because it is a fundamental question: if there is any defined behavior
> possible if a variable
> > contains an invalid value. I consider a value outside of the declared
> range as invalid, if it shall
> > be valid, change the declaration of the type.
>
> _AND_ remove types that can't have reasonably cheap range checks like
> sparse
> enums ? :-)
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