[REBOL] Re: Private words in objects?
From: tim-johnsons::web::com at: 6-Jul-2006 13:30
* Gabriele Santilli <gabriele-colellachiara.com> [060706 01:14]:
> Hi Gregg,
>
> On Wednesday, July 5, 2006, 6:16:09 PM, you wrote:
>
> GI> You *can* do it today, but it takes extra effort. I thought I would do
> GI> it a lot, once I figured out how (with the help of people here), but
> GI> I've never used it in a production system.
>
> The way Gregg is mentioning is just using a "hidden" context for
> your "protected" words.
>
> Example:
>
> use [private-field] [
> private-field: 2
> my-obj: context [
> public-field: 1
> set-field: func [val] [
> private-field: val
> ]
> get-field: does [
> private-field
> ]
> ]
> ]
This is very 'use'ful to know!
FYI: this is like the lisp use of 'let
in the "upper level"
Greg should put it in the cookbook..
> The disadvantage is that you can't easily clone the object (that
> wouldn't clone the other context, so that would be shared by all
> clones), so you need a constructor function. However there is no
> way for you to change PRIVATE-FIELD by mistake.
> (Note that there are many ways to achieve this result, so it
> really depends on what's best in your specific case.)
It would be interesting to see other examples.
cheers
tim
--
Tim Johnson <tim-johnsons-web.com>
http://www.alaska-internet-solutions.com
