Re: Sugestion to Multiple Inheritance

[Jim Rogers <jimmaureenrogers@worldnet.att.net>]

Lutz Donnerhacke wrote:

> 
> Let's try to code this:
> 
> package Sorts is
>    function Sort (col : Collection) return Collection is abstract;
>    procedure Sort (col : in out Collection) is abstract;
> end package Sorts;
> 
> with Sorts;
> package Stable_Sorts is
>    function Sort renames Sorts.Sort;
> end package Stable_Sorts;
> 
> with Sorts;
> package Inplace_Sorts is
>    procedure Sort renames Sorts.Sort;
> end package Stable_Sorts;
> 
> with Stable_Sorts, Inplace_Sorts;
> package Stable_Inplace_Sorts is
>    procedure Sort renames ?;
> end package;


Since the only sort procedure available to rename is
Inplace_Sorts.Sort, that must be the procedure you want to
rename. If, on the other hand, the Stable_Inplace_Sorts.Sort
must work with both the Stable_Sorts.Sort function and the
Inplace_Sorts.Sort procedure, you must not rename anything.
You must define the way those two Sort subprograms interact.
This means defining an entirely new Sort procedure for the
package Stable_Inplace_Sorts. This is one of the problems NOT
solved by multiple inheritance.

In fact, in this example, Stable_Inplace_Sorts would have
access to all the subprograms defined in Sorts. It would be
clearer to simply "with" or inherit from the Sorts
package directly.

Jim Rogers
Colorado Springs, Colorado USA