[REBOL] Re: fun with for loops
From: lmecir:mbox:vol:cz at: 2-Aug-2002 23:04
Hi Charles,
if I understood correctly, you would like to have:
set-words: function [
{Get all set-words from a block}
block [block!]
] [elem words] [
words: make block! length? block
parse block [
any [
set elem set-word! (
insert tail words to word! :elem
) | skip
]
]
words
]
cfor: function [
{a C-like for function}
[throw]
init [block!]
test [block!]
inc [block!]
body [block!]
] [use-words cont] [
use-words: append set-words init [continue]
body: append reduce [:catch body] inc
cont: reduce [does [throw none]]
use use-words reduce [
:set [continue] cont
:do init
:while test body
]
]
Usage:
cfor [i: 1] [i <= 3] [i: i + 1] [
if i = 2 [continue]
print i
]
1
3
-L
----- Original Message -----
From: "Charles"
Howdy folks. Got a bit of a difficulty here. Say I'm evaluating a for
loop, like reading lines of text from a file. At the beginning of my for
loop,
I have it check to see if the line is commented, blank, or neither. If it's
commented or blank, I want it to just skip to the next iteration of the for
loop; however, if it's neither, let it keep going. I would prefer to do
this
with a simple if [] as opposed to a heavy either [][]... 'break' doesn't do
what I need - it kills the for loop entirely, instead of skipping to the
next
iteration. If I use either [][], I have to do:
either condition? [
if true do this
][
if false
do these
next 20 lines
all indented
with more indentation
yet to come
very long lines
]
You follow me? It's a coding habit I've picked up from another language.
Thanks folks.
--Charles
