[REBOL] Re: A question in time saves... Clouds???
From: carl:cybercraft at: 5-Jun-2001 21:57
Hi Jim,
I see while I've been writing this that Graham's given you a function
to wait on a time, but perhaps some of the following will still be of
use to you...
On 05-Jun-01, Jimbo wrote:
> Hi again,
> It's the Happy Hippy back with another question.
> Please forgive my repeated intrusions. O :-)
Heh - you're the silver-lining, man. (:
> I'm still working on the same automated cloud catcher.
> I've expanded it (cut & paste) to grab all nine sections
> needed for the cloud cover of the /entire/ earth which
> was my original goal. Everything is working OK except
> that the time required to do the nine grabs varries
> from set to set. So I got looking into it and it apears
> as if I can use the "WAIT" command with a block of times
> in brackets. I wonder... Is this true? If so what would
> it be formatted like? I feel pretty silly here, not even
> knowing basic REBOL syntax :-/
> Ummm...
> wait [time1, time2 time3,
> time4, time5, time6]
> ???
Apart from the commas (not needed in REBOL) the syntax is fine, except
it still won't work. (How you use a block with 'wait I'm not sure -
can't find much in the manuals on 'wait...) But read on...
> and what does a time string look like? I could find wait 100 which
> is no. of seconds and I was shown wait 10:20:30, HH:MM:SS. How about
> a specific time like 11:32 PM ?
First, a quick way to see a REBOL date+time is to just type "now" at
the Console...
>> now
== 5-Jun-2001/19:57:11+12:00
And if you examine the 'now word it shows how you get at the various
bits of it...
>> ? now
USAGE:
NOW /year /month /day /time /zone /date /weekday /precise
DESCRIPTION:
Returns the current local date and time.
NOW is a native value.
REFINEMENTS:
/year -- Returns the year only.
/month -- Returns the month only.
/day -- Returns the day of the month only.
/time -- Returns the time only.
/zone -- Returns the time zone offset from GMT only.
/date -- Returns date only.
/weekday -- Returns day of the week as integer (Monday is day 1).
/precise -- Use nanosecond precision
So, to see a time value enter...
>> now/time
== 20:05:49
As I see it, there's two ways to approach your problem. One would be
to write a bit of code to wait on times in a block, (as you'd hoped
'wait could do and perhaps it can:), or use REBOL's 'modified? word
to check the URLs every ten minutes or so to see if the JPGs have
changed since you last downloaded them...
>> ? modified?
USAGE:
MODIFIED? target
DESCRIPTION:
Returns the last modified date of a file or URL.
MODIFIED? is a function value.
ARGUMENTS:
target -- (Type: file url)
(SPECIAL ATTRIBUTES)
catch
Something like this might work (code not checked)...
old-time: now
forever [
file-time: modified? url-name
if file-time <> old-time [
get-clouds-routine
old-time: file-time
]
wait 00:10:00
]
That depends on you being able to get the file's modified time though
- with some files on the Net you don't seem to be able to.
As to using a block of times, something like this could perhaps be
used (I've tested this - Esc to Exit.)...
times: [00:00:05 00:00:04 00:00:03 00:00:02 00:00:01]
forever [
; Main code here
wait first times
print first times
times: next times
if empty? times [times: head times]
]
That doesn't wait for a certain time of day though, (others will have
to tell you how to do that), so you might have to always start your
script on the hour - till you work out how to create the 'times block
based on the time you run your script. (:
Have fun.
--
Carl Read
[carl--cybercraft--co--nz]
