Re: Hopefully simple question regarding generics

[mcsun!hp4nl!gufalet.let.rug.nl!rug4!laverman@uunet.uu.net (Bert Laverman]

Jack Beidler writes:
> ...
>he is using private types.  It might be wise to create a "limited private" ver
sion of this
>Sort,
>
>generic
>    type Object_Type is limited private
>    type Array_range is (<>) ;
>    type array_type is array (Array_range) of Object_Type ;
>    with function "<" (left, right: Object_Type return boolean ;
>    with procedure SWAP (left, right : in out OBJECT_TYPE) ;
>procedure Sort (An_Array : in out AArray_Type) ;
>
>which would need a procedure, like SWAP, to flip the object references around.

Actually, the Modular Pascal standard library shows that even this interface ca
n be
cut down:

	PROCEDURE sort(lo, hi: integer;
		       FUNCTION before(i, j: integer): boolean;
		       PROCEDURE swap(i, j: integer));

If you've already taken the test and the swapping out of the sorter, why keep t
he array?
This way the sorter is at the minimal need-to-know situation. This form of prog
ramming
generics has more the aspect of frame-work reuse, than routine-reuse.

Okay, okay. So maybe an Ada compiler will want to expand those generic paramete
rs
inline. Still, I think this is an excellent example of use of procedural parame
ters,
and in most cases the loss caused by the procedure calls will be minimal.

Greetings, Bert
-- 
#include <std/disclaimer>

  Bert Laverman,  Dept. of Computing Science, Groningen University
  laverman@cs.rug.nl			bert@arrakis.nl.mugnet.org