Re: (elementary question) Test on type ?

["Marin David Condic" <dont.bother.mcondic.auntie.spam@[acm.org>]

You can get there via a variety of ways. One of my favorites is to declare
an abstract tagged private type that has "+", "-", etc. as abstract
functions. You can then use a generic formal that is of the 'Class of that
tagged type. A user then derives from the abstract class and supplies the
operations. That saves you from making a long generic formal list at the
expense of making a long abstract function list. Don't know that there is a
huge advantage to either one.

But none of the possible solutions is as "clean" as simply having a "type X
is scalar ;" generic formal parameter. (or some similar mechanism.) If Ada
is smart enough to detect the operations for the actual parameter anyway,
then maybe I don't have to do the work. That's always A Good Thing.

MDC
--
Marin David Condic
Senior Software Engineer
Pace Micro Technology Americas    www.pacemicro.com
Enabling the digital revolution
e-Mail:    marin.condic@pacemicro.com
Web:      http://www.mcondic.com/


"Mark Biggar" <mark.a.biggar@home.com> wrote in message
news:3B951F33.927CA445@home.com...
>
> You can do almost what you want using a generic package using a private
> generic type and explicitly defining the operators you want to use.
> For example if your package only needs "+", "*", "-", "=", "<".
>
> generic
> type Scalar is private;
> with function "+"(Left, Right: Scalar) return Scalar is <>;
> with function "="(Left, Right: Scalar) return Boolean is <>;
> with function "-" ... ;
> with function "<" ... ;
> package Special_Math is
> ...
> end Special_Math;
>
> package Special_Int is new Special_Math(Scalar => Integer);
> package Special_Float is new Special_Math(Scalar => Float);
>