Re: Ada way to read/write to character file

["Nick Roberts" <nickroberts@adaos.worldonline.co.uk>]

"Alfred Hilscher" <Alfred.Hilscher@icn.siemens.de> wrote in message
news:3C39BB2B.57F2BB3D@icn.siemens.de...

> I think it's because Text_IO is designed for sequential files where it
> does not make sense to switch between reading and writing. For what you
> want do you should use "Direct_IO" which provides an open mode
> "Inout_file".
>
> e.g. package Com_IO is new Direct_IO (Character); -- hope this works as
> intended

No, no, no! This won't vaguely work. Michael wants to use a serial device
for (bidirectional) sequential text I/O. Ada.Direct_IO is for random binary
file access (totally different!).

> Michael Bode wrote:
> >
> > Hi,
> >
> > I'm wondering if there is an Ada way (i.e. standard package) to read
> > and write to a character mode (sequential) file like the COM?:
> > resp. /dev/ttyS? interface. Ada.Text_IO has no read/write file mode
> > and with GNAT I wasn't able to connect two File_Type variables to the
> > same physical file at the same time.
> >
> > I want to communicate with a device hanging on the RS232 port. I have
> > to write to the device and read the answers. I could of course do it
> > like open, write, close, open read, close, open,... But I think this
> > is not very elegant. I just finished doing it with the Win32
> > resp. POSIX API functions, but I'm still wondering if it could be done
> > with some standard Ada package.

I think the answer to this question is, unfortunately, "No".

Personally, if I were writing an Ada.Text_IO implementation for MS-DOS (or
Windows) or an *n[iu]x, I would have made damn sure it could be used
(bidirectionally) with the character devices, but there's nothing (and there
could not sensibly have been anything) in the RM95 compelling any
implementation to do so.

--
Best wishes,
Nick Roberts