From: Dmitry A. Kazakov <mailbox@dmitry-kazakov.de>
Subject: Re: Modes (was unbounded_string)
Date: Mon, 13 Oct 2003 11:28:48 +0200
Date: 2003-10-13T11:28:48+02:00 [thread overview]
Message-ID: <hlrkovgfspku7epl2j5586g1ut6ih5os41@4ax.com> (raw)
In-Reply-To: x7v4qygi6qw.fsf@smaug.pushface.org
On 11 Oct 2003 08:16:39 +0100, Simon Wright <simon@pushface.org>
wrote:
>Dmitry A. Kazakov <mailbox@dmitry-kazakov.de> writes:
>
>> declare -- I need the value of QUERY_STRING here
>> Temp : String renames Getenv ("QUERY_STRING").all;
>> -- Temp is an alias to the env-string. You cannot modify it.
>> -- Yet it is not a pointer. An analogue would be C++ reference
>> begin
>> ... -- Doing with Temp everything I can to do to
>> -- a constant String
>> end; -- I don't need it anymore
>
>Actually you *can* modify it:
>
> with Ada.Text_IO; use Ada.Text_IO;
> with GNAT.OS_Lib; use GNAT.OS_Lib;
>
> procedure Env is
> Temp : String renames Getenv ("COLDFRAME").all;
> begin
> Temp (1) := 'x';
> Put_Line (Temp);
> end Env;
>
>then
>
> smaug.pushface.org[5]$ COLDFRAME=foo ./env
> xoo
>
>(GNAT 3.16a1)
>
>Should GNAT.OS_Lib.Getenv have been defined as returning a constant
>string access?
>
> type Constant_String_Access is access constant String;
No, if Jeffrey Carter (see his post) is right and the result is
presently allocated on the heap, then it is a very bad design.
Clearly Getenv should either return an Unbounded_String or a plain
String.
---
Regards,
Dmitry Kazakov
www.dmitry-kazakov.de
next prev parent reply other threads:[~2003-10-13 9:28 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20031010074015.761204C40C1@lovelace.ada-france.org>
2003-10-10 8:27 ` Modes (was unbounded_string) Andrew Carroll
2003-10-10 9:15 ` Dmitry A. Kazakov
2003-10-11 7:16 ` Simon Wright
2003-10-13 9:28 ` Dmitry A. Kazakov [this message]
2003-10-10 15:18 ` Stephen Leake
2003-10-10 16:21 ` Martin Dowie
2003-10-14 18:47 ` Craig Carey
2003-10-10 19:06 ` Jeffrey Carter
2003-10-13 9:33 ` Dmitry A. Kazakov
2003-10-13 9:40 ` Stephane Richard
2003-10-13 10:12 ` Dmitry A. Kazakov
2003-10-15 2:16 ` Warren W. Gay VE3WWG
2003-10-15 3:36 ` Jeff C,
2003-10-16 16:45 ` Warren W. Gay VE3WWG
[not found] <20031010094017.680474C40C1@lovelace.ada-france.org>
2003-10-10 10:58 ` Andrew Carroll
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