Re: Modes (was unbounded_string)

["Warren W. Gay VE3WWG" <ve3wwg_nospam@cogeco.ca>]

"Stephane Richard" <stephane.richard@verizon.net> wrote in message
news:rquib.4914$zw4.1688@nwrdny01.gnilink.net...
> "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> wrote in message
> news:94skovca8efqisiip65q37of63g28n1284@4ax.com...
> > On Fri, 10 Oct 2003 19:06:00 GMT, Jeffrey Carter <spam@spam.com>
> > wrote:
> >
> > >Since GNAT.OS_Lib.Getenv returns type String_Access, you have to use
> > >String_Access if you want to use Getenv. But note the description of
> > >Getenv from GNAT.OS_Lib:
> > >
> > >--  Get the value of the environment variable. Returns an access
> > >--  to the empty string if the environment variable does not exist
> > >--  or has an explicit null value (in some operating systems these
> > >--  are distinct cases, in others they are not; this interface
> > >--  abstracts away that difference. The argument is allocated on
> > >--  the heap (even in the null case), and needs to be freed explicitly
> > >--  when no longer needed to avoid memory leaks.
> >
> > Awful, I didn't expected that from ACT. The design above is definitely
> > not Ada's idiom.
...
> Perhaps as in many OS it's the only way as the OS (probably written in C or
> some other language simply returns it this way?


Well, C returns a pointer, if you use getenv(2). However, there is no reason
that ACT could not have converted this into a normal Ada string, which is
what I would have expected. Even in C, you are really expected to use
putenv or setenv to make a change. However, programmers have been
known to "cheat" and modify the string that the getenv pointer points to,
which works provided that the string does not require more length. But
even in C terms, IMHO, this is a bad practice.

-- 
Warren W. Gay
http://home.cogeco.ca/~ve3wwg