[REBOL] Re: Pointers, Context in Rebol 3.0 (For the real Rebol Lovers)
From: anton::wilddsl::net::au at: 24-Mar-2007 12:01
You can change the body code of the function
> a1: func [a b] [a / b]
>
> inst1: make template [f1: :a1]
> inst2: make template [f1: :a1]
>
> I expect that both inst1 and inst2 share the same "pointer to a1"
a1 and f1 in each instance refer to the same function, yes.
> Performing a:
>
> a1: func [a b] [a / b + 1]
>
> should change both INST1/f1 and INST2/f1 because they should point to the
> same function as I have declared [F1: :A1]. Instead only a1 is changed
> because a1 is copied during object creation and not pointed.
You could do this:
inst1: make template [] set in inst1 'f1 :a1
inst2: make template [] set in inst2 'f1 :a1
Another way is to put functions in a sub-object,
just like face/feel. eg:
template: context [
aaa: 1
funcs: context [f1: none f2: none]
]
a1: func [a b] [a / b + 1]
template/funcs/f1: :a1
inst1: make template []
inst2: make template []
inst1/funcs/f1 3 4
inst2/funcs/f1 3 4
These are a little bit uncomfortable.
I think automatic copying in MAKE was a mistake.
MAKE previously shared functions (ie. did not copy them).
At the time of the discussion, people were confused
about how VID worked and shared/copied its facets.
I didn't have a strong opinion then because I wasn't
sure myself, but these days I have a strong opinion
of copying. --- AVOID it, because you can't "uncopy"
afterwards.
Regards,
Anton.
