🚀 go-pugleaf

Dick Lane at !ucbvax!ucdavis!u-mt!lane writes:

> Within S, a sink file will capture output excepting plots.  When the device
> is "printer", I would like have character plots sent to a log file for later
> printing.  Is there an easy modification to S to allow this ??
> 
> I can get a printable plot by starting S as follows
> 		(  cat -u -  |  S  )   |   tee  script.file
> but I want something simpler for my students to use.

The reason that printer plots cannot be redirected to sink files is a
technical one rather than a conceptual one.  The printer device driver
is a separate process that stays running as various S functions are
executed.  In order to affect the printer driver, the sink function
would need to communicate the sink file name to the printer driver so
that it could open the file.  With two separate processes writing the
same file, it would be important to make sure buffers were flushed to
avoid intermingling printer plot output with other output.

A more general solution would be to have a graphics redirection command
that allowed the output of any device driver to be captured in a file.
It might be patterned after the defer() function, which sends a file
name to the device driver.   I've got it on my list of things to do,
but there are lots of other things on that list, too.
-- 

    Rick Becker  alice!rab  research!rab