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From: "Nick Roberts" <Nick.Roberts@dial.pipex.com>
Subject: Text input on a console
Date: 1997/04/26
Message-ID: <01bc524d$a0fe21a0$28f982c1@xhv46.dial.pipex.com>#1/1
X-Deja-AN: 237542551
References: <01bc49c1$c8c990a0$c47d8ea1@AaBbCcDd>
 <01bc4d85$4c127b40$f4f582c1@xhv46.dial.pipex.com> <E961o5.AuL@thomsoft.com>
Organization: UUNet PIPEX server (post doesn't reflect views of UUNet PIPEX)
Newsgroups: comp.lang.ada
Date: 1997-04-26T00:00:00+00:00
List-Id: <comp.lang.ada>




Keith Thompson <kst@sd.aonix.com> wrote in article
<E961o5.AuL@thomsoft.com>...
> In <01bc4d85$4c127b40$f4f582c1@xhv46.dial.pipex.com> "Nick Roberts"
<Nick.Roberts@dial.pipex.com> writes:
> > The answer is to use 
> > 
> >    Get_Line(Command);
> > 
> > instead of just
> > 
> >    get(command)
> > 
> > Reason why: things getting stuck in the buffer.
> 
> That's the problem, but it's not the solution.
> 
> In the previously posted program, Command is an object of an enumeration
> type.  There is no Get_Line procedure for enumeration types (though it
> wouldn't be difficult to write one).


I blunder again. Sorry (the little yellow tablets strike again).

However, this does raise another point, of more general interest. The
behaviour of a program when inputting text from a console is relatively
undefined in Ada (as in most languages). It may be impracticable to try to
formally define things more closely (i.e. in the RM), but it may be
sensible to informally define things a little bit more than the RM,
somehow.

When GET is used to read a string, or other type, from the console, should
the program wait for a carriage-return ('cooked' or 'buffered' mode) or
just get the characters directly ('raw' mode)? Should special characters
(like backspace, control-D, control-Z, ESC, etc.) be automatically
supported? Should there be some agreed parameters in the FORM parameter to
specify this sort of thing? (And, in which case, what do we do about
STANDARD_INPUT?)

Comments welcome.

Nick.