Re: Feature request - assignment in expressions

[Juergen W. <wie...@fr...>]

Am Dienstag, 8. Mai 2007 schrieb Ethan A Merritt:
>    plot <foo>  using 1:2 after track_max($2) with lines

[...]

> - (Con) This is incompatible with the revised zooming/refresh code
>   that I am working on.  There the idea is to avoid re-reading the input
>   data if all you want to do is replot it.  But the assign/after mechanism
>   is applied during data input, so it would be bypassed by any such
> shortcut.

I think this is a feature.  For compatibility, the refreshing should
not be done with "replot" but with "redraw" (or similar).  I would
not expect "redraw" to go through this filter.

> I have never understood the time-handling code.  I suspect that the
> whole special case time format mechanism is no longer needed, as the same
> goal can be achieved using general string-handling functions.
> In your case, you probably need to use some combination of stringcolumn()
> strptime() strftime() rather than setting a time format.

I don't think so.  I see two problems (probably there are more):
* Automatic tic generation is date/time aware.  This could be
  adjusted manually, but the automatic tics wouldn't be too sensible.
* Tic label generation.  The command "set format" just takes a
  format string, which is used either for date/time or ordinary
  numbers.  The functions strptime() and strftime() only work with a
  more flexible "set format" which takes a string valued expression, which
  is evaluated at plot time.

Juergen