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From: Brian Rogoff <bpr@shell5.ba.best.com>
Subject: Re: signatures
Date: 1999/07/29
Message-ID: <Pine.BSF.4.10.9907292015080.15361-100000@shell5.ba.best.com>#1/1
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Date: 1999-07-29T00:00:00+00:00
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On Thu, 29 Jul 1999, Ehud Lamm wrote:
> Suppose I want to ensure that a to be written set of routines all
> conform to a given signatre (let's say all sort routines have the
> signature 
> generic
>    type item is private;
>    type list is array(positive range <>) of item; 
> procedure sort (s:in out list);
> )?
> 
> What is the preffered way of doing this?

My preferred way would be

generic 
    type Item_Type is private;
    type List_Type is array(Positive range <>) of Item_Type;
    with procedure Sort(S : in out List_Type) is <>;
package Sort_Signature is end;

then instantiate this with some types and a sort procedure. You can use
this package as a package parameter to an implementation package like the 
following.

generic 
    with My_Sort is new Sort_Signature(<>);
package My_Package is 
... etc

A very nice addition to Ada over Ada-83, these package parameters and
signature packages!

-- Brian