Re: Idiom for a class and an object in Ada

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

Marin David Condic wrote:
> Interesting, but I think it misses my question. In your first package:
> General_Classes - if you had 5 specific objects of type Class and they
> are totally static (something that exists from the moment you hit the
> first instruction to the moment the power goes down and you *really*
> need them to be in global memory) - where would you declare the five
> objects of type "Class" as you've defined it?
>
> How to do it is simple:
>
> Object_1 : General_Classes.Class ;
> Object_2 : General_Classes.Class ;
> Object_3 : General_Classes.Class ;
> Object_4 : General_Classes.Class ;
> Object_5 : General_Classes.Class ;
>
> In what context would you put those objects?

Inside a package body with access routines. These routines tend to be the 
project-specific ones. They /may/ be portable to other systems but are less 
likely to be portable than a class that models the behaviour of those types 
of registers. But in your 5 A-D examples, and assuming that the 5 A-D were 
on a particular device, I would consider make the package name the device 
name.

If there was some issue with having to assign the registers into a 
processors particular area of memory that couldn't be done via an address 
clause but could only be done via a compiler/linker command, then I have 
separated out the data items into their own package spec - to avoid the 
access routines also being mapped into that area. The package names were 
suffixed "_GD" (for Global Data) and the coding rules were that only the 
package without the "_GD" could 'with' them and then only from the package 
body.

-- Martin