Re: Generics - Difference between ADA and Modula--3

[Jeffrey Carter <jrcarter@acm.org>]

David Starner wrote:
> 
> for I in 1 .. 50 loop
>         declare
>                 A: array (0 .. I) of Integer;
>         begin
>                 ...
>         end;
> end loop;
> 
> where there's a varying array. Or alternately:
> 
> type bob is array (integer range <>) of foo;
> ...
> while (complex_condition) loop
>         declare
>                 Token: bob := Something_Returning_A_Varying_String;
>         begin
>                 ...
>         end;
> end loop;

A very common version of this is

declare
   S : String := PragmARC.Get_Line;
begin
...

(Shameless plug: see the PragmAda Reusable Components at

http://home.earthlink.net/~jrcarter010/pragmarc.htm

).

S may be from zero to Positive'Last characters long. In Ada, you only
really need explicit memory allocation and deallocation for things like
unbounded dynamic data structures, such as linked lists. In C you need
them whenever the size of something is not known at compile time.

It should also be noted that controlled types can be used for automatic
deallocation of explicitly allocated memory, getting much of the
advantage of garbage collection with the predictable run times of manual
memory management.

-- 
Jeff Carter
"Go and boil your bottoms."
Monty Python & the Holy Grail