Re: Enum or Named Number

["Martin Dowie" <martin.dowie@btopenworld.com>]

"Jeff" <jeff.huter@bigfoot.com> wrote in message
news:fe4bb2c2.0404060930.f932668@posting.google.com...
> Looking for implementation advise.  I'm writing a binding to some C
> code that has several defined number macros (e.g. #define Viewable 1)
> for states and flags.  I would like to bitwise-or these numbers in Ada
> which leads me to believe I should define these as named mod numbers
> such as below:
>
> type State is mod 2**Interfaces.C.Int'Size
> State1 : constant State := 2#0001#
> State2 : constant State := 2#0010#
> State3 : constant State := 2#0100#
>
> Any reason to define these as an Enum with a representation clause?
> Seems like there would be more plumbing code.  For example, I believe
> that I would need to write my own bitwise-or function for the Enum.
>
> Is the named number implementation the way to go, or is there a better
> way?

Depends on a couple of things:

1) are you trying to provide a thick or thin binding?
2) can the "states" really mutually exclusive or can they be 'set' at the
same time?

If the answer to 1) is "thick binding" and 2) is "really mutually exclusive"
then I would take the hit and declare an Ada enumeration and use a lookup
table to get the C representation.

Otherwise, I think I'd just stick with the above.

-- Martin