Re: save "|gpsavediff >a.gp"

[Hans-Bernhard B. <br...@ph...>]

On Mon, 20 Oct 2003, Petr Mikulik wrote:

> I wanted to let the "save" command to save to file only differences wrt
> "reset"  status of gnuplot, so I've patched save_command() + surrounding
> routines to allow write to pipe. In the attached file, there is that
> patch + my favourite script "gpsavediff".

I'm somewhat surprised it doesn't already support the "| command" syntax
already.  Given that, I'm all for integrating this patch ASAP.

> Do you do such a diff-save in a similar way?

Yes.  I salvaged a script similar to yours ages ago, from a mail to
info-gnuplot IIRC.  It's called 'reduce-gnuplot-output', it's a
csh script (of all things), and it only works for named files.

A better approach to the whole task would almost certainly be to integrate
it into gnuplot itself.  But for that to become feasible, we'ld need a
massive refactoring of the whole internal status stuff:

*) organize the set/show/save/unset/reset implementations by variable, not
   by command, i.e. the set, show, save, unset and reset (default status)
   for a given setting should all be in *one* place, not scattered over
   4 files (set.c,show.c,unset.c,misc.c).  This would make things a
   lot more OO-ish.

*) Add a new method, or a flag to the 'save-variable' method of each
   setting, so it saves only the state different from the default.

*) Add an option to 'save', or a new command 'savediffs' to call that
   new method.

This would be a ton of work, unfortunately.  I.e. I'd advise to delay this
until after the 4.0 release we all still agree should happen soon ---
right?

-- 
Hans-Bernhard Broeker (br...@ph...)
Even if all the snow were burnt, ashes would remain.