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World: r3wp

[Core] Discuss core issues

Gabriele
2-Sep-2007
[8686x2]
i'd actually suggest retry [f1] 4  or   retry [f2] 4   with my code. 
 :f also works but if f takes arguments it would break. so it's cleaner 
to just always use a block.
actually, there is one problem with return, which is if you want 
to do   retry [... return 'something ...]  and have it return from 
the calling function, not retry (like if cond [return 'something]). 
to allow that, you need to add the [throw] func attribute, ie. retry: 
func [[throw] code times] ...
DanielSz
2-Sep-2007
[8688x2]
Thanks for the advice, Gabriele, I'll play around with it for a while...
Gabriele, I'm trying to understand in what kind of situation a throw 
is required. f1: func [] [if true [return "something"]] works without 
a throw, for example. Can you provide a concrete example of code 
that requires the throw attribute to 'retry? Thanks!
Gabriele
3-Sep-2007
[8690x3]
i'm not sure it is needed or not for retry. it depends on how you 
use it.
f: func [] [
    retry [
        ; do something...
        if cond [return something-else]
        ; ...
    ]
    some-val
]
if you want the return inside retry to return from F and not RETRY, 
then you need [throw].
DanielSz
3-Sep-2007
[8693]
Thanks, Gabriele, I haven't thought about that.
Joe
4-Sep-2007
[8694x3]
is the sort block dialect broken ?
b-test: ["xxx" "V" 4 "xxx" "M" 3 "yyy" "Laaaa" 2 "yyy" "Lbbbb" 2 
"yyy" "Kaaaa " 2 "yyy" "Haaaa" 2 "yyy" "Aaaaa" 2]

									print ["init               " mold b-test]

sort/skip/compare b-test 3 [reverse 3 2] 			print ["reverse 3 2  
      " mold b-test]

sort/skip/compare b-test 3 [reverse 3 reverse 2]	print ["reverse 
3 reverse 2" mold b-test]
It seems to use the first reverse 3 but ignore the second comparator. 
Any ideas ?
btiffin
4-Sep-2007
[8697x2]
Joe;  I think you need to pass sort/compare a function! not a block! 
 The function template is [a b] and returns true or false or whether 
to swap.  Something like
sort/compare data func [a b] [a > b]

(Note: the names a and b could be any words but the function is called 
with two arguments).
Never mind my blabbering.  Learned something new today.  :)
Graham
5-Sep-2007
[8699]
Can someone remind me how bind a bunch of words to a different context? 
 I want to use the named colors in a special context.
Chris
6-Sep-2007
[8700]
colors: context [red: 255.0.0 green: 0.255.0 blue: 0.0.255]
reduce bind [red green blue] in colors 'self
Graham
6-Sep-2007
[8701]
I'll give it a go :)
[unknown: 5]
6-Sep-2007
[8702]
anyone know if REBOL runs on PocketPC?
Graham
6-Sep-2007
[8703x2]
core used to ...
wince 1.1 ?
james_nak
6-Sep-2007
[8705]
I don't know if the CE version does but: http://www.rebol.com/platforms-core.html
 (Note: these are oldies but goodies)
btiffin
7-Sep-2007
[8706]
Graham;  To quickly get all the colours, try
rebol []


do-thru http://www.rebol.org/library/scripts/capture.rcapture on 
help tuple! capture off
colors: copy []
parse to block! find get-captured newline [
    some [set col word! (append colors col) word! tuple!]
]

;; This will fail, no context
print disarm try [get first colors]
;; Now bind the words to the REBOL context
bind colors 'red  print get first colors
Gregg
10-Sep-2007
[8707]
Joe, did you try "[reverse 3 forward 2]" as your comparator?
btiffin
11-Sep-2007
[8708]
Request for opinions;  What would you rather read? 
   var: none
...
   var: either flag [value] [none]
or 
   var: if flag [value]


Assuming var can safely be none or a value but the init may not be 
close to the code.
Graham
12-Sep-2007
[8709x2]
var: pick [ value ] flag
was I allowed that option??
btiffin
12-Sep-2007
[8711]
Certainly, but that would not bounce out at me during a quick grok...perhaps 
with exposure.
Chris
12-Sep-2007
[8712]
var: all [flag value]
Gregg
12-Sep-2007
[8713]
I favor EITHER or ALL for this, in general.
Izkata
12-Sep-2007
[8714]
I'd go with the 'either or the 'if
Graham
12-Sep-2007
[8715]
Forth does it the pick way to avoid using logic
Ashley
12-Sep-2007
[8716]
'all is faster than 'if or 'either ... also more "extensible" in 
that it scales, as in:

	var: all [flag1 flag2 flag3 value]
	var: any [flag1 flag2 flag3 value]
btiffin
12-Sep-2007
[8717x2]
Thanks for the opinions gentlemen.  All over the map of course.  
But Gregg's matters most, so either it is.  :)   And I've found the 
either to be the easier grok when quick scanning, no double think 
required.  This is not in tight code, so readability wins over performance 
concerns.


And just an aside;  all [false false] returning none...kinda sucks. 
  all [none none] returning none, sure; but all [false true] should 
be false, not none.  Or change the help doc to ...and returns NONE 
at the first FALSE or NONE.  Well, it doesn't suck persay, it just 
doesn't behave as the help would suggest.
Oh, now Ashley fills in more of the picture as I was typing.  Seeing 
as I can use either or all, perhaps I'll start getting used to all 
for this idiom. :)
Chris
13-Sep-2007
[8719x2]
It's like 'if in that regard though.  'if returns none when the condition 
is false...
I guess 'all could be considered "all or nothing".
btiffin
13-Sep-2007
[8721]
Yeah, I was just griping about docs.  :)  none is fair return, and 
consistent for all cases, pun intended.
Henrik
13-Sep-2007
[8722]
this is spinning my brain:

foreach [a b] [1 2 3 4] [print get load "a"]
** Script error: a has no value

How do I bring "a" under the correct context?
Gregg
13-Sep-2007
[8723]
foreach [a b] [1 2 3 4] [print get bind load "a" 'b]
Henrik
13-Sep-2007
[8724]
gregg, thanks, it works :-)
Joe
13-Sep-2007
[8725]
Gregg, thanks, forward worked ! It's hard to know without documentation. 
How did you know ?
Gregg
14-Sep-2007
[8726]
Joe, Sorry, I thought you must have found the docs, since you got 
as far as you did. :-)

http://www.rebol.com/docs/core25.html#sect4.1.4.
james_nak
14-Sep-2007
[8727]
How do you clear out a local variable within a function? I have this 
scenario and I can't get the function to run more than once. I could 
copy the contents to a temp var but that seems silly.

a: func [ some-var /local s] [

	s: "example %text% string"
	replace/all s "%text%" some-var
]

Once I run this thing "s" never gets its orginal value.
Thanks
Alberto
14-Sep-2007
[8728]
s: copy "example %text% string"
james_nak
14-Sep-2007
[8729]
So simple. Thanks Alberto. Estas en Mexico?
Alberto
14-Sep-2007
[8730]
así es
james_nak
14-Sep-2007
[8731]
DF?
Alberto
14-Sep-2007
[8732x2]
sí, en el DF
tu dónde estás?
james_nak
14-Sep-2007
[8734]
Estoy en California acerca de Los Angeles.
Alberto
14-Sep-2007
[8735]
ok, podríamos pasar al grupo "rebol spanish" :)