[REBOL] Re: object funnies
From: joel:neely:fedex at: 19-Oct-2001 15:06
Hi, again, Rod and Graham,
Rod Gaither wrote:
> Much as I like REBOL I find this departure from
> the typical "Scope" behavior of other languages
> counter intuitive ...
>
> >I'm actually left wondering why RT chose to implement it in
> >this way. It's not intuitive, and nor is it discussed in
> >the online core docs.
> >
There are lots of different ways in REBOL to create contexts (and
please forgive me if I insult your intelligence... ;-) The thing
that REBOL does is let us manipulate context/"scope" relationships
in ways that are not as convenient (or in some cases possible) in
other languages. Consider this example:
factory: make object! [
population: 0
artifact: make object! [
myself: none
x: 42
clone-me: func [xx] [
population: population + 1
make myself [x: xx]
]
]
artifact/myself: artifact
census: func [] [print ["There are" population "artifacts."]]
]
ur-artifact: factory/artifact
When CLONE-ME inside of ARTIFACT refers to POPULATION it is really
intended for it to be a word named POPULATION that belongs to a
distinct context (that of FACTORY), not automagically creating a new
one within the context of ARTIFACT itself. Thus we can do
>> tom: ur-artifact/clone-me 17
>> dick: tom/clone-me 357
>> harry: dick/clone-me 999
>> factory/census
There are 3 artifacts.
Since the definition of an OBJECT! can take place within a variety
of other constructs that also create contexts, it would be limiting
to have *every* set-word within the object (regardless of nesting)
interpreted as pertaining to the object's context.
Of course, this throws us back into the Fundamental Equation of
Legitimate Empowerment:
capability = responsibility
otherwise known as TANSTAAFL !-}
-jn-
--
This sentence contradicts itself -- no actually it doesn't.
-- Doug Hofstadter
joel<dot>neely<at>fedex<dot>com
