Re: Converting Char to Enum

[Jeffrey Carter <jrcarter@acm.org>]

Lars Noschinski wrote:
> 
> Kilgallen@SpamCop.net (Larry Kilgallen) wrote:
> > Lars Noschinski <lars@usenet.noschinski.de> writes:
> >>   convert : constant array(characters) of symbols := ...
> [...]
> >> "sym := convert(char)"?
> >>
> >> In this case, how I catch invalid characters?
> >
> > Perhaps with one additional symbol named INVALID_CHARACTER.
> 
> Ok, that's a possibility. But I thougt, inband-signalling would be a no-
> no?

If it makes your code more complex, then avoiding inband signaling is
probably the wrong approach.

In real life, you would use the extra enumeration value only in the part
of the code that interfaces with the outside world. The rest of the
software would be restricted to a subtype (Valid_Symbol?) of the
enumeration type that excludes this extra value.

-- 
Jeff Carter
"Nobody expects the Spanish Inquisition!"
Monty Python's Flying Circus