Re: Callback on clock

Nenad Stepanovic (
Wed, 12 Mar 1997 11:08:09 +0100

To subscribers of the xforms list from Nenad Stepanovic <> :

Steve Lamont wrote:
> I'm not sure I understand the question completely but if you mean to
> make a call from an XForms Clock callback to set the system clock
> through adjtime(2) or settimeofday(2) then even if you could do it
> there would be no point since I'm pretty sure the XForms Clock object
> gets its time from time(3) -- in other words, the system's clock.
> The XForms Clock is only reporting to you its notion of what the
> system's time of day is, thus using it to set the system's time of day
> is somewhat pointless -- in fact if you did succeed in doing so you'd
> no doubt degrade the accuracy of the system clock since the round trip
> between querying the time and setting it would introduce a soon
> noticable delay.
> If you perhaps mean using some sort of point and click interface to
> move the hands of the XForms Clock and thereby change the system's
> time of day, then you might be able to do this by setting a pre- or
> post-handler and interact with the Clock that way. Offhand I don't
> know if it will work but you could give that a try. Otherwise, the
> manual specifically says "No interaction takes place with clocks."
> They're read-only objects.
When I created XForms Clock, I added callback from xforms GUI, but I
couldn't activate it by clicking on Clock.
The XForms Clock gets system time that can be set with command "date"
from command line.
> No, but you probably need to refer an external time base of some sort,
> such as a WWV (or other national/international time standard)
> receiver. The program also has to be setuid root, since only root is
> allowed to change the system clock.
When I asked if there is some problem with X, I thought about some
timers, (eg. screen saver was activated when I changed system time).
Few years ago, I had a big problem with changing system time on SCO
while running some demon for keeping system time in network (timed,
ntpd...). Few seconds more-less is not so important in my case (system
("date...") could be fine).

>From the first day on faculty, the professors was talking that you could
get "anywhere" from "here" if you really want to.

Nenad Stepanovic
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