[REBOL] Re: Translate this code into real Rebol?
From: joel::neely::fedex::com at: 23-Jan-2002 23:40
Hi, Brett,
Brett Handley wrote:
> make context [fibohelp: none] [
> set 'fibonacci func [n [integer!] /test][
> fibohelp: func [n [integer!] /local a b] [
> a: 0 b: 1
> while [n > 0] [a: (b: b + a) - a n: n - 1]
> print ["by the way the value of test is:" mold test]
> a
> ]
> either all [negative? n even? n] [
> - fibohelp abs n
> ] [
> fibohelp abs n
> ]
> ]
> ]
>
> The good thing is Fibohelp can utilise words from Fibonacci's
> namespace... The assumed thing is that there is no redefinition
> occurring every call.
>
AFAICT that's a bad assumption, and the above is just a more
complicated way of saying
fibonacci: func [n [integer!] /local fibohelp] [
fibohelp: func [n [integer!] /local a b] [
a: 0 b: 1
while [n > 0] [a: (b: b + a) - a n: n - 1]
a
]
either all [negative? n even? n] [
- fibohelp abs n
][
fibohelp abs n
]
]
which actually *does* redefine FIBOHELP every time FIBONACCI is
invoked.
Both of the above versions run about four and a half times
slower than the version (posted earlier) created with USE.
(I removed the /TEST refinement and related PRINT before
running the timing tests so that I/O lag wouldn't affect
the results.)
-jn-
--
; sub REBOL {}; sub head ($) {@_[0]}
REBOL []
# despam: func [e] [replace replace/all e ":" "." "#" "@"]
; sub despam {my ($e) = @_; $e =~ tr/:#/.@/; return "\n$e"}
print head reverse despam "moc:xedef#yleen:leoj" ;
