Re: Using the GNAT defined attribute: 'Enum_Rep

["Marin David Condic, 561.796.8997, M/S 731-96" <condicma@PWFL.COM>]

Robert A Duff <bobduff@WORLD.STD.COM> writes:
>In article <97082719523509@psavax.pwfl.com>,
>Marin David Condic, 561.796.8997, M/S 731-96 <condicma@PWFL.COM> wrote:
>>    The ARM suggests using Unchecked_Conversion to get from here to
>>    there, but now you've got to create an integer type that is the
>>    same size as the enumerated type. Here's a code fragment:
>
>How about:
>
>    type Temp_Integer is range 0..2**User_Types.CL_Evt_Status'Size;
>
>and use Temp_Integer'Base?  Or:
>
>    type Temp_Integer is mod User_Types.CL_Evt_Status'Size;
>
>?
>
    That's pretty clever. Never thought of attempting to use the 'Size
    attribute in the type definition. I guess I had my brain wrapped
    around the axle with trying to use the 'Size attribute in the
    representation clause.

    Still, it would be very useful to have an attribute that is the
    inverse of 'Enum_Rep, taking a universal integer parameter and
    returning the corresponding enumeral - raising Constraint_Error if
    the integer did not match an enumeral internal representation. (Or
    possibly not raising the exception? Let it work a little like
    Unchecked_Conversion?)

    Thanks for the tip.

    MDC
Marin David Condic, Senior Computer Engineer     ATT:        561.796.8997
Pratt & Whitney GESP, M/S 731-96, P.O.B. 109600  Fax:        561.796.4669
West Palm Beach, FL, 33410-9600                  Internet:   CONDICMA@PWFL.COM
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