Re: Ada requires too much typing!

["Yannick Duchêne (Hibou57)" <yannick_duchene@yahoo.fr>]

Le Wed, 09 Jun 2010 23:22:53 +0200, Maciej Sobczak  
<see.my.homepage@gmail.com> a écrit:
> Or maybe not generics in general, but the specific approach to
> generics that was chosen by Ada.
> Remember, in C++ this is not a problem:
>
> #include <vector>
> #include <list>
>
> template <class ContainerOfInts>
> void appendThreeInts(ContainerOfInts & c)
> {
>     c.push_back(7);
>     c.push_back(42);
>     c.push_back(123);
> }
>
> int main()
> {
>     std::vector<int> vec;
>     std::list<int> lst;
>
>     appendThreeInts(vec);
>     appendThreeInts(lst);
> }
>
> The appendThreeInts function uses the implicit common interface, even
> though vector and list do not share anything explicitly.
>
> --
> Maciej Sobczak * http://www.inspirel.com
>
> YAMI4 - Messaging Solution for Distributed Systems
> http://www.inspirel.com/yami4

Although it would requires a different layout (actually, just more typing  
;) ), the same is possible with Ada : just use a formal subrpogram  
parameter for pubsh_back.

You would better use the notation:
    with My_Subprogram (...signature...) is <>;
or even (left oftenly, while still valid and meaningful)

    with My_Subprogram (...signature...) is null;
to get benefit from static polymorphism.

About this kind of generic formal parameter, please, see [ARM 2005 12.16  
(2.1/2)] and [ARM 2005 12.16 (10)] and [ARM 2005 12.16 (10.1/2)].

Static polymorphism is achieved when you use a consistent naming shame for  
similar subprograms in different areas or packages : ex. you define a  
Lists package with a Push procedure and a Stacks package with a Push  
procedure also (same name in both package).

All of these, providing I have really understood what you were requesting  
for.

-- 
There is even better than a pragma Assert: a SPARK --# check.
--# check C and WhoKnowWhat and YouKnowWho;
--# assert Ada;
--  i.e. forget about previous premises which leads to conclusion
--  and start with new conclusion as premise.