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From: "=?ISO-8859-1?Q?Egil_H=F8vik?=" <egilhovik@hotmail.com>
Newsgroups: comp.lang.ada
Subject: Re: Generic Zero Length Array
Date: Fri, 22 Feb 2008 05:53:19 -0800 (PST)
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Date: 2008-02-22T05:53:19-08:00
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On Feb 22, 2:31=A0pm, shaunpatter...@gmail.com wrote:
> I have a bit of legacy code in my system that I am trying to remove
> all warnings from.
>
> The package is a generic -- with:
>
> type Element is (<>);
> type Element_List is array (Indexing range <>) of Element;
>
> I have been stumped by one compiler warning where one of the functions
> needs to return a zero-length empty generic array:
>
> warning: variable Result_String is read but never assigned
>
> code:
>
> if Error_Condition then
> =A0 declare
> =A0 =A0 type Result is new Element_List (Indexing.First + 1 ..
> Indexing'First);
> =A0 =A0 Result_String : Result;
> =A0 begin
> =A0 =A0 =A0return Element_List (Result);
> =A0 end;
> end if;
>
> How do I initialize this array when I can't know what type it is or
> will be?
>
> Thanks
>
> --
> Shaun


A new generic parameter Null_Element would do the trick, but
that means changing code wherever the generic is used...

type Element is (<>);
type Element_List is array (Indexing range <>) of Element;
Null_Element : Element;


then you could rewrite the above code to

if Error_Condition then
  return Element_List'(Indexing'First..Indexing'First-1 =3D>
Null_Element);
end if;


--
~egilhh