World: r3wp

Perfect! thank you Maxim 8-)

its fun to have easy questions some times  (note: easy is not synonymous 
to obvious  ;-)

well, I've spent almost an hour trying to figure out.. next time 
I'll go stright to the dictionary!

some functions are not names the same as in CS so even that sometimes 
leads you away from what you'd expect.... in this case the dash in 
the name prevented me from finding it in google for hours.

names = named

and I knew it existed!

It sometimes help to find the right REBOL words by calling help with 
part of the word. Like:
>> ? line
>> ? new

.

What is the best way to get an formatted timestamp that matches IBM 
DB2 in this form: ccyy-mm-dd-hh:mm:ss.nnnnnn

I tried this, but I'm stuck on how to extract out the nanoseconds 
from Now/precise:


Timestamp: rejoin [ now/year "-" now/month "-" now/day "-" now/time 
".000000" ]


Also, if the month or day is less than 2 digits, I need a leading 
zero -- how can I do this easily?

To get the seconds:
third now/time/precise
Use first, second, to get HH MM.
Not sure it is nano-second precise!

This adds leading zeroes to MM or DD -- you could use similar logic:

http://www.rebol.org/cgi-bin/cgiwrap/rebol/view-script.r?script=to-iso-8601-date.r

precision depends on the OS used, but millisecond precision is displayed 
always, AFAIK.

I got the following when I did this:

rejoin [now/year "-" now/month "-" now/day "-" now/time "." third 
now/time/precise "000" ]

2007-7-17-13:40:36.36.748000 which is pretty close, except the seconds 
are repeated again.

Try this:

 rejoin [now/year "-" now/month "-" now/day "-" first now/time "." 
 second now/time "." thir
d now/time/precise "000" ]

But you may need to add some more trailing zeroes.... a time of 01:02:03.100 
would show in REBOL as 1:2:3.1

That seems to work -- except for adding leading zeroes which can 
be done via above script -- Thanks Sunanda

I have a format func that isn't on REBOL.org (yeah, I know...; it 
requires another func, etc.) if you have to do a lot of formats and 
don't want to roll them all. Anyway, let me know if you want me to 
send it Patrick.

Sure -- Why not  -- I'm learning more and more all the time

OK -- I'm perplexed as to when does things get evaluated.

If I have a variable like Now-TS: to get the formatted time, it will 
be resolved immediately and return the time.

If later, after I wait 1 second, I want to print the new formatted 
timestamp, it returns the exact same value as before, when I know 
the time has acutally changed.  How do I get the time now to be resolved 
again?  Example code:

print now/precise		gives 17-Jul-2007/14:35:21.308-5:00 
 wait 1

 print now/precise		gives 17-Jul-2007/14:35:22.324-5:00	now/precise 
 is evaluated immediately

 Now-timestamp: 
	rejoin [
		Now/year "-" Now/month "-" Now/day "-" 
		first Now/time "." second Now/time "." third Now/time "000" ] 

 print Now-timestamp			gives	2007-7-17-14.35.22.0000	
 wait 1 

 print Now-timestamp			gives	2007-7-17-14.35.22.0000		the exact same 
 time -- not evaluated immediately


Is it this way because Now-timestamp has been assigned and already 
evaluated  -- if so, how do I have it reevaluate it again?

Wrap it in a function.
now-timestamp: does [rejoin [...]]

Ok, so if a variable is unset, then it is evaluated when defined.

If it is already defined, then it is not evaluated again unless there 
is a do or does?  Is that right?

Super -- that worked just great

DOES is a shortcut for creating a function, DO evaluates its value 
directly. A variable is not evaluated when assigned - the value is, 
and then it is assigned to the variable. You don't really "define" 
variables in REBOL, but the distinction may be more complicated than 
you need to worry about for now.

You might consider that the time will march on during the course 
of your evaluation, so you might want to store it in a local variable, 
like this:


pad0: func [x n [integer!]] [head insert/dup (x: form :x) "0" (n 
- length? x)]
now-timestamp: func [/local n] [n: now/precise rejoin [

    pad0 n/1 4 "-" pad0 n/2 2 "-" pad0 n/3 2 "-" pad0 n/4 11 "000"
]]

Sorry, that won't work in some cases. Try this instead:

now-timestamp: func [/local n s] [
    n: now/precise
    s: n/4/3
    s: join either s < 10 ["0"] [""]
    s: head insert/dup tail s "0" 9 - length? s
    rejoin [
        pad0 n/1 4 "-" pad0 n/2 2 "-" pad0 n/3 2 "-"
        pad0 n/4/1 2 ":" pad0 n/4/2 2 ":" s
    ]
]

missing an s :(

s: join either s < 10 ["0"] [""] s

Thanks Brian.  I will play around with it a little more.  Just to 
re-iterate my understanding of rebol assignments


A variable is not evaluated when assigned - the value is, and then 
it is assigned to the variable. You don't really 
define" variables in REBOL"

So at the time of assignment, the text following the : is assigned 
to the variable but is not evaluated.  That is to say the variable 
is like a pointer to the text string that was typed in.

Does that mean that Rebol will not do evaluations until it needs 
to.  For example:
In-file:	%file_path_name.txt
In-text:	Read In-file

write %out-file-path-name.txt In-text		<-- this is where the evaluation 
occurs to resolve all the above?  Is that right?

Another similar example:

In-file:	%file_path_name.txt
In-text:	Read In-file

append In-text 'this-is-the-end-of-the-file	<-- evaluated because 
of action word append
write %out-file-path-name.txt In-text

is that right?

That's not what I meant. I meant that the expression to the right 
of the set-word (s:) is evaluated. The result of that evaluation 
is the value that will be assigned to the word. So, you were right 
the first time about the evaluation order.

The word itself is not evaluated though, it is just assigned. The 
value that the word was assigned is returned from the assignment 
expression too, so that you can chain assignments or use the value 
later, like I did in pad0 above.

Later on you can either do a full evaluation of the word by stating 
it directly ( a ) or you can just retrieve its value by using a get-word 
( :a ).

REBOL variables don't really need to be declared, as such, but you 
do need to declare function parameters and object fields. Some of 
the REBOL language look like they are declaring variables, but they 
really are doing something different.

Thanks for your patience with me.  I'm wrong about the evaluation. 
 It is done at the time of the assignment returing whatever value 
to the variable.  The reason Now-timestamp had identical values, 
even after waiting 1 second was that it was evaluated once, with 
a value put into it, then the wait happened, then I simply re-printed 
the same value as before, because I did not re-do the variable.  
I think I was making it harder than it really is.

I don't understand this statment:

Later on you can either do a full evaluation of the word by stating 
it directly ( a ) or you can just retrieve its value by using a get-word 
( :a )


Are you saying that I can simply type Now-timestamp to have it re-evaluated 
at that time?

Umm, not quite.  You're getting into it now.  :)  Sometimes it helps 
to think of it this way (but it is actually 'deeper')    myprint: 
print   won't work, it tries to evaluate print, but myprint: :print 
 "gets" the value of print and then you can  myprint [1 2 3]   - 
again it's deeper than what I just explained.

a: 23 * 56   when interpreted will compute 23 * 56 then the set-word 
 a:  assigns the value 1288 to the variable a.  Because it is just 
a number  a  and  :a  are both 1288, you can't really get at the 
23 * 56 anymore, that expression has been evaluated and "forgotten", 
forgotten not really a good word, but the expression 23 * 56 is not 
around anymore, only the 1288.

Patrick; I just looked back a little bit, your question about formatted 
time-stamps...Chris has donated an awesome date time formatter to 
the rebol.org repository.  Very close to strftime in function.  Check 
out


http://www.rebol.org/cgi-bin/cgiwrap/rebol/view-script.r?script=form-date.r

form-date now/precise "%C%y-%m-%d-%H:%M:%S"  doh!  loses the precise, 
so...

dt: now/precise  t: dt/time  rejoin [form-date dt "%C%y-%m-%d-%H:%M:%S" 
find form t/second "."]


again, not quite right...the precision won't be right padded with 
zeros, one more step

dt: now/precise   t: dt/time   t: find form t/second "." 

rejoin [form-date dt "%C%y-%m-%d-%H:%M:%S" head change/part ".000000" 
t length? t]

I think I'll bug Chris to add %P for precise padded seconds.  :)

and of course   head change/part COPY ".000000" ... if you reuse 
the sequence...It'd be nice to be able to just use form-date now/precise 
"%C%y-%m-%d-%H:%M:%P"

Patrick;  Never mind for now...the %S is rounded, won't work.  Sorry 
for the interruption.

btiffin -- Thank you for taking the time to explain it.  I think 
I understand it now.  I was initially confused because I tried to 
print a timestamp knowing full well that time is changing and I didn't 
understand how to get it evaluated.  I confused the assignment of 
a value with that of a function..  Good info on the date timestamp 
above.

Thank you all!

If you read the Core manual on REBOL.com, it has a pretty good explanation 
of the four word types (normal, lit, set, and get). The other thing 
to understand is when blocks, and nested blocks, are reduced (evaluated). 
That can be tricky to figure out sometimes, because funcs like PRINT 
do it automatically.


If you can get a handle on when things are evaluated--and don't stress 
when you have to add a REDUCE or COMPOSE but aren't sure why--and 
if you can grok the four word types, you 'll be in great shape.

When getting started, you can quite often treat REBOL like many other 
languages; it has a nice facade to let you get a lot done that way 
without forcing you to understand how it really works.

rebol.org %form-date.r updated...

Fix for time-stamps and a really nice short-cut that includes the 
zone.
%c
 outputs all the fields of now/precise  nicely formatted
%s
 outputs the seconds with nanosecond precision  nicely formatted

form-date now/precise "%C%y-%m-%d-%H:%M:%s" is now all you need for 
IBM DB2 time-stamps.

javascript dates??

Whoey whatty?  :)  These are all zero-padded.  Addition of the "%#H" 
type sequences wouldn't be too-too hard.

javascript dates are milliseconds since 1-Jan-1970

doing this in math causes a few problems!

We decided to use %s for REBOL precision...no epoch seconds in form-date. 
 And yeah, I was looking at the TIME and NTP protocols...it would 
not be fun in high level REBOL, I don't think even Rebcode could 
poke the right fields for time!

Moving to Library...