[REBOL] Redefining system words - gotchas
From: tim-johnsons:web at: 26-Apr-2007 14:01
Howdy:
Here's an example:
I want to redefine 'pick so that pick series -1 gets the last element
pick series -2 gets the second to last etc...
If the source for my redefined 'pick is in a file, let's call it std.r
and we have the following code:
sys-pick: get in system/words 'pick
Now if 'sys-pick is in my code for the redefined 'pick and
I do %std.r a second time before closing the interpreter, I will
get a stack overflow because on the second 'do 'pick is already
redefined.
The workaround for this is:
if not value? 'sys-pick[
sys-pick: get in system/words 'pick
]
the works, but the gotcha is that if I'm working with a large application
that has somehow previous defined 'sys-pick errors could be introduced.
This scenario is not likely, especially if one sticks to a strict taxonomic
convention of redefining system words as 'sys-word, but I'd welcome
comments on this situation.
thanks
tim
Long live the mailing list :-)
--
Tim Johnson <tim-johnsons-web.com>
Palmer, Alaska, USA
