Re: Ada enumerations

[jm59@prism.gatech.edu (John M. Mills)]

"Stanley R. Allen" <s_allen@hso.link.com> writes:

>Matthew Heaney wrote:

>> No, Ada doesn't come with an attribute to return the representation of an 
>> enumeration literal, because it doesn't need to!

> At the risk of seeming shrill, I'll
>repeat myself: what good reason can there be for
>allowing me to *specify* enumeration representations
>but denying me the ability to easily *query* them also?

Interfacing to hardware (or to hardware simulated by software in some other
language) may be made much more readable through enumerations named for
the functions they perform ("Set_Mode( Op_Modes.Idle );") where the actual bit
configurations for the controls are not at the disposition of the programmer.

That _is_ a reason to explicitly assign; I don't claim it means you shouldn't
be able to _query_ for representation.  However there was a related thread in
which a user complained about not being able to add an integer to an enumerate
(and gave an example yielding a value which apparently was _not_ among the
enumerate's defined representations).  I see every reason to discourage that
sort of code.  This sounds about as risky as attempting to add pointers in C.

-- 
John M. Mills, Senior Research Engineer   --   john.m.mills@gtri.gatech.edu
   Georgia Tech Research Institute, Georgia Tech, Atlanta, GA 30332-0834
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