Re: Storage space question

["David C. Hoos, Sr." <david.c.hoos.sr@ada95.com>]

Matthew Heaney wrote in message ...
>Marin David Condic <condicma@bogon.pwfl.com> writes:
>
>> > As long as you only use the constants (not the literals), you get all
>> > the type safety that an enumeration type buys you.
>> >
>> > Which is why rep clauses for enumeration types is overkill, that adds
>> > unnecessary complexity to the language.
>>
>> Well, not quite all the type safety. Suppose that the field occupies 3
>> bits but only the values 0, 1 and 2 are currently valid. Or worse, only
>> the values 2#001#, 2#010# and 2#100# are valid. With an integer type,
>> there is no way of eliminating the invalid values. With enumerations,
>> you can't accidentally get an invalid bit pattern assigned to the
>> register field.
>
>"As long as you only use the constants (not the literals), you get all
>the type safety that an enumeration type buys you."
>
>The object will never get assigned the values 3 .. 7, because those
>values aren't named by constants.
>
>If you stick to the constants, then there is no loss of type safety.
>
Well, what if the data structure was filled by, say, a read from a network.
Use of the enumeration allows you to apply the 'valid test.