Re: [Gcl-devel] si::info works again on Windows

[Camm Maguire]

Thanks Peter!  Mike, work-around aside, is this behavior causing you
problems elsewhere?  And if so where?

Take care,

Peter Wood <address@hidden> writes:

> On Fri, Mar 19, 2004 at 03:37:02PM +1000, Mike Thomas wrote:
> 
> > I believe that there is a deeper problem READ-LINE which has remained hidden
> > since at least the end of 2002.
> > 
> > On Windows READ-LINE at the console doesn't wait for input; it just sees the
> > end of the line after the (READ-LINE) and returns an empty string. I believe
> > this may be CR related and I intend to look into it before Monday, time
> > permitting.
> > 
> > If there is some text immediately after the (READ-LINE) it returns that
> > text.
> 
> Hi
> 
> This has been READ-LINE's behaviour for a long time.  I have found
> references to it in the KCL mailing list from 1988! :-)
> 
> It's also mentioned in the documentation (in gcl-si) ...
> 
> <start quote>  
> 
> Note that when using line at a time input under unix, input forms will
> always be followed by a #\newline. Thus if you do
> 
> >(read-line) "" nil
> 
> the empty string will be returned. After lisp reads the (read-line) it
> then invokes (read-line). This happens before it does anything else
> and so happens before the newline character immediately following
> (read-line) has been read. Thus read-line immediately encounters a
> #\newline and so returns the empty string. If there had been other
> characters before the #\newline it would have been different:
> 
> <end quote>
> 
> It is easy to work around, if you want to discard any chars waiting in
> the input stream and just get user input you can do:
> 
> (defun rl ()
>   (do ()
>       ((not (listen)))
>     (read-char-no-hang))
>   (read-line))
> 
> I don't know if it's a bug, but it probably surprises anybody
> encountering it for the first time.
> 
> Regards,
> Peter
> 
> 
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> 
> 
> 

-- 
Camm Maguire                                            address@hidden
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