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From: "Jean-Pierre Rosen" <rosen@adalog.fr>
Newsgroups: comp.lang.ada
Subject: Re: I/O - exception handling
Date: Mon, 26 May 2003 16:52:39 +0200
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Date: 2003-05-26T16:52:39+02:00
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"Sergey Koshcheyev" <serko84@hotmail.com> a �crit dans le message de news:bat3ee$2ec$1@ns.felk.cvut.cz...
[..]
> procedure Read_Something (...) is
>    use Ada.Text_IO;
>    use Ada.Strings.Unbounded;
>    use Ada.Strings.Unbounded.Text_IO;
>    --  GNAT-specific package, I believe
>
>    File : File_Type;
>    S1, S2 : Unbounded_String;
>
> begin
>    Open (File, Name => "test.txt", Mode => In_File);
>    Get_Line (File, S1);
>    Get_Line (File, S2);
>    Close (File);
>
> exception
>    when others =>
>       if Is_Open (File) then
>          begin
>             Close (File);
>          exception
>             --  Close can raise exceptions too!
>             when others => null;
>          end;
>       end if;
> end Read_Something;

Doing so will make the exception disappear. You exception handler should rather read:
 exception
    when others =>
       if Is_Open (File) then
          begin
             Close (File);
          exception
             --  Close can raise exceptions too!
             when others => null;
          end;
       end if;
       raise;   -- Reraise the original exception, even if you had another exception at close
 end Read_Something;

> However, this looks ugly to me, since I have to close the file in two
> places, and also guard for exceptions while handling exceptions. Is there a
> better solution or is this sort of thing OK in the Ada way?
>
> Sergey.
>
>