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From: Ludovic Brenta <ludovic@ludovic-brenta.org>
Newsgroups: comp.lang.ada
Subject: Re: Array Help?
Date: Thu, 01 Mar 2012 08:16:18 +0100
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Date: 2012-03-01T08:16:18+01:00
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Robert A Duff writes on comp.lang.ada:
> Robert A Duff <bobduff@shell01.TheWorld.com> writes:
>
>> % ./array_test
>>
>> raised SYSTEM.ASSERTIONS.ASSERT_FAILURE : predicate failed at array_test.adb:14
>
> Actually, I just realized there's a workaround for the slice problem.
> The following does not raise any exception.
>
>   procedure Array_Test is
>
>      type Integer_Array is array (Positive range <>) of Integer
>        with Dynamic_Predicate => Integer_Array'First = 1;
>
>      procedure Foo (Param : in out Integer_Array) is
>      begin
>         null;
>      end Foo;
>
>      A : Integer_Array (1 .. 10) := (others => 0);
>
>      subtype Slide is Integer_Array(1..6);
>   begin
>      Foo (Slide(A (3 .. 8)));

Doesn't that involve copy-in and copy-out between the slice and a
temporary object of type Slide?  Grossly inefficient, methinks.

>   end Array_Test;
>
> But that's kind of tricky; I wouldn't do that without copious
> comments.  And some constants or something to avoid violating the DRY
> principle.

Yes.  For Adam: DRY=Don't Repeat Yourself.

-- 
Ludovic Brenta.