Re: Usage of Interfaces with Ada 95

[Michael Erdmann <Michael.Erdmann@snafu.de>]

Matthew Heaney wrote:

> Michael Erdmann <Michael.Erdmann@snafu.de> writes:
> 
>> ........ I my example i like to provide a package
>> enumerator where the developer X can put in his data type, but the
>> gerneric package forces him to implement the interface for his data
>> type and nothing else. If the semantic of this interface is simple, it
>> will be mutch easier for somebody else to maintain the code written on
>> this concept.
> 
> You still haven't groked the static polymorphism idea.
> 
> If I have the following generic algorithm:
> 
>   generic
>      type Iterator_Type is private;
>      with function Succ (Iterator : Iterator_Type)
>        return Iterator_Type is <>;
>      with procedure Process (Iterator : Iterator_Type) is <>;
>      with function "=" (L, R : Iterator_Type)
>        return Boolean is <>;
>   procedure Generic_Algorithm (First, Back : Iterator_Type);
> 
> Then of course this is going to check how iterators are declared by
> independent developers -- as soon as he tries to instantiate the generic
> algorithm.  Any iterator any developer builds must conform to this
> logical interface.

Thanks for your example!

I assume, that the procedure Generic_Algorithm is containing some kind 
of implementation of an iterator based on the input parameters of the 
generic?

You are right, this provides a standarized interface, but i guess the 
procedure Generic_Algorithm contains some kind of implementation of an 
iteration based on the methods specified in the input?
I think the is a different view on the topic by defining a functionality
of an interface, providing a generic implementation which defines the 
interface for the programmer. This was exactly what i dont like to 
do. I dont like to spent the effort of breaking down a concept into 
a generic implementation. This is the reason why i like to use interfaces.

Regards
    M.Erdmann