Re: Ada Popularity: Comparison of Ada/Charles with C++ STL (and Perl)

["Robert Kawulak" <tigrisek@interia.pl>]

Hi,

> This "same interface" is not a language object. It is a fiction, which
> cannot be described in language terms independently on its implementation.
> So you physically unable to program in terms of this interface. It simply
> does not exist.

  It's not a fiction, it's a kind of agreement. The language doesn't see
this interface directly, but you can use it. And if you try to violate it in
a place where conformance to this interface is crucial, your program won't
compile.

> What can you do with vector<>? Operator[] defined on it is
> not a function. It is a template function.

  Function template, you mean ;-)

> You cannot call it outside of
> another template. That template must in turn have the vector's element
> type
> as a parameter etc.

  So what? You just make a template instead of a function and the job is
done. In all the places you call this template function, a compiler
generates appropriate function from your template looking at the type of
it's arguments, and that's it.

>> so it's easy to write a code that copes with vectors of
>> elements of different types.
>
> Really? Write code which reads from the stream a type X (from some
> defined,
> but large set of types) and then returns empty vector<X>.

  Of course this can be done (Turing complete... ;-), but this is a very
different kind of problem, isn't it? It's just like reading a type X and
returning an object of type X. I don't think this would be much simpler if
std::vector<> was implemented as runtime-polymorphic, not using generics. Of
course there's the need to create a runtime-polymorphic wrapper class for
std::vector<>, but the problem of choosing the appropriate type from a large
set given this type's name as a string is the same in both cases. Besides
can you do this better in Ada than in C++? (Or it wasn't your point to
compare C++ with Ada in this respect, just to compare runtime vs. static
polymorphism?)

> Stepanov? (:-))

  Could you give some references (links, book titles...)? I became curious
(but it doesn't mean you've already convinced me ;-).

With regards,
Robert