Re: Anonymous array not allowed as components

[joakimds@kth.se]

Den fredag 1 november 2019 kl. 09:32:42 UTC+1 skrev L Dries:
> I have an need for an array of Unbounded_Strings in which i define the 
> elements.
> 
> I declared it as:
> 
>        Debug_Proc   : array (1 .. nr_Proc) of Unbounded_String :=
>          (Debug_Proc(Lan),
>           To_Unbounded_String("Only"),
>           To_Unbounded_String("Empty_Buffer"),
>           ...
>           etc.
> 
> Then I got the message:
> 
> 65:22 Anonymous array not allowed as components
> This results i a position just before "array"
> 
> The value nr_Proc is defined in another package.
> Debug_Proc(Lan) is an Unbounded String
> I tried to replace nr_Proc by a value. The same result.
> I tried to replave the value of the first Unbounded String by "--", 
> again no result
> I tried set it as an constant array, also no result.
> 
> What do I do wrong?
> -- 
> L. Dries

Hello L. Dries,

Unbounded_String is well-known for being "slow" because it does unnecessary heap-allocations. To avoid performance penalty the XString type has been defined in the GNATColl library. The point is that one should have very good reasons to use Unbound_String in one's application and not use it needlessly.

In your case what you want is to map each integer in an interval to a specific String. If that's the case I recommend taking advantage of expression functions and case statements introduced in Ada 2012:

type Index is new Integer range 1 .. nr_Proc;

function Debug_Proc (I : Index) return String is
(case I is
  when 1 => "Only",
  when 2 => "Empty_Buffer", ...);

or maybe it is:

function Debug_Proc (I : Index) return String is
((case I is
  when 1 => "Only",
  when 2 => "Empty_Buffer", ...));

The compiler will tell you.

Best regards,
Joakim