R devel - May 2010 - Location of source code for readline()

A few days ago on R-help I asked about a cross-platform timeout version of
readline().
Some suggestions, but only partial joy so far. I can get the Gnu bash  'read
-t ...' to
work in Windows by using the 'bash -c ' construct, but then R's
system() function does not
seem to allow this to pass through. Similarly a Perl and Free Pascal routine
that I tried,
the latter being a single executable that did the prompt and the timeout. (I can
send code
offline if anyone interested -- not fully protected against bad inputs,
however.)

Now I'm wondering where the code for readline is located in the R source.
I've tracked as
far as the 'do_readln' in names.c, but now want to find the actual code
to see if I can
patch it, though I am a real novice in C. Suggestions welcome.

My application, FYI, is to have a script that will display something, and wait
for a
keypress (for readline it seems to need the Enter key) but timeout after a
preset number
of seconds. The setTimeLimit "almost" works -- but not for readline.
I'm thinking of a
modified readline like readline(prompt='Do you want to continue?',
timeout=6).

Note that the issue seems to be Windows. I haven't a Mac to try, but Linux
can be made to
function by various methods at the top.  Sigh.

JN

On 2010-05-30 15:33, Prof. John C Nash wrote:
> A few days ago on R-help I asked about a cross-platform timeout version of
readline().
> Some suggestions, but only partial joy so far. I can get the Gnu bash 
'read -t ...' to
> work in Windows by using the 'bash -c ' construct, but then R's
system() function does not
> seem to allow this to pass through. Similarly a Perl and Free Pascal
routine that I tried,
> the latter being a single executable that did the prompt and the timeout.
(I can send code
> offline if anyone interested -- not fully protected against bad inputs,
however.)
>
> Now I'm wondering where the code for readline is located in the R
source. I've tracked as
> far as the 'do_readln' in names.c, but now want to find the actual
code to see if I can
> patch it, though I am a real novice in C. Suggestions welcome.
>
> My application, FYI, is to have a script that will display something, and
wait for a
> keypress (for readline it seems to need the Enter key) but timeout after a
preset number
> of seconds. The setTimeLimit "almost" works -- but not for
readline. I'm thinking of a
> modified readline like readline(prompt='Do you want to continue?',
timeout=6).
>
> Note that the issue seems to be Windows. I haven't a Mac to try, but
Linux can be made to
> function by various methods at the top.  Sigh.
>
> JN
>
I can't help with your project, but check scan.c for do_readln.

  -Peter Ehlers