[REBOL] Re: Embedded objects.
From: joel:neely:fedex at: 12-Mar-2003 20:51
Hi, Terry,
Terry Brownell wrote:
> Sunanda has the solution, but thinking there must be a more graceful
> approach? Perhaps not.
>
Hmmmm... But Sunanda's explicit proviso points out a severe
limitation of this approach.
> -----Original Message-----
> From: [rebol-bounce--rebol--com] [mailto:[rebol-bounce--rebol--com]]
> On Behalf Of [SunandaDH--aol--com]
>
> Here's one way -- with the usual proviso that it isn't the same Bob
> -- we've replaced one with another. ^^^^^^^^^^^^^^^^^^^^^^
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> BobsDog: make object! [name: "Rex"]
> Bob: make object! [name: "Bob"]
>
> Bob: make Bob reduce [to-set-word 'BobsDog BobsDog]
>
> Bob/BobsDog/Name
> == "Rex"
>
Consider,
Bob: make object! [name: "Bob"]
Carol: make object! [name: "Carol" husband: Bob]
which allows...
>> Carol/husband/name
== "Bob"
However, if we now replace Bob with another object to create the
new attributea:
BobsDog: make object! [name: "Rex"]
Bob: make Bob reduce [to-set-word 'BobsDog BobsDog]
we can do...
>> Bob/BobsDog/name
== "Rex"
But now look at this!
>> Carol/husband/BobsDog
** Script Error: Invalid path value: BobsDog
** Near: Carol/husband/BobsDog
>> mold Carol
== {
make object! [
name: "Carol"
husband:
make object! [
name: "Bob"
]
]}
This is the same discussion from a few weeks ago: replacing an object
by a different object only updates the reference where the replacement
took place; all of the other references to the original object still
refer to the original.
If you want everybody who knows Bob to know that Bob got a dog, you'll
have to do *some* amount of planning ahead.
-jn-
--
Polonius: ... What do you read, my lord?
Hamlet: Words, words, words.
_Hamlet_, Act II, Scene 2
