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From: "Sergey Koshcheyev" <serko84@hotmail.com>
Newsgroups: comp.lang.ada
Subject: Re: I/O - exception handling
Date: Mon, 26 May 2003 19:48:46 +0200
Organization: Czech Technical University
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Date: 2003-05-26T19:48:46+02:00
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"Preben Randhol" <randhol+abuse@pvv.org> wrote in message
news:slrnbd4hqk.2hh.randhol+abuse@kiuk0152.chembio.ntnu.no...
> OK understand. *I* would then do:
>
>    procedure Safe_Close (File : File_Type)
>    is
>    begin
>       if Is_Open (File) then
>          begin
>             Close (File);
>          exception
>             --  Close can raise exceptions too!
>             when others => null;
>          end;
>       end if;
>    end Safe_Close;
>
>
>    procedure One_Of_Your_Procedures_That_Open_Files
>    is
>    begin
>       Open (File, Name => "test.txt", Mode => In_File);
>       Get_Line (File, S1);
>       Get_Line (File, S2);
>
>       Safe_Close (File);

I'd change the line above to just "Close (File);", to have the opportunity
to handle any error raised by Close.

>    exception
>       when others =>
>          Safe_Close (File);
>    end Read_Something;
>
> Now you can use the Safe_Close in any function you like.

I thought of this solution, but here the problem is code duplication. In
this case it doesn't matter, but what if there were several files? You'd
have a procedure Close_All and a procedure Safe_Close_All, which would both
contain similar code.

But I guess the perfect general solution doesn't exist in Ada. By the way,
it seems to exist in C++, which is sort of strange, shouldn't it be the
other way around? ;-) Your solution seems close enough to perfect, however,
so that's probably what I'd use.

Sergey.