My latest guess, found after digging around in the mailing lists and looking
at information on how to create private object slots, is to use 'uses' to
declare a local variable to hold the old value..
child-object: make parent-object [
uses [old-somefn] [
old-somefn: get 'somefn
somefn: func [ .. ][
.. old-somefn ..
]
]
]
It appears a lot less brittle, since old-somefn is now local to
child-object, and objects derived from child-object can use the same
pattern. Does anyone know of a special case that would break this? (Beyond
redefining 'uses' in a parent.. )
--Scott.
-----Original Message-----
From: Volker Nitsch [mailto:[EMAIL PROTECTED]]
Sent: Friday, April 27, 2001 12:09 AM
To: [EMAIL PROTECTED]
Subject: [REBOL] Re: Objects, Inheritance and Barking Up Wrong Trees?
>>>>>>>>>>>>>>>>>> Urspr�ngliche Nachricht <<<<<<<<<<<<<<<<<<
Am 26.04.01, 04:02:32, schrieb "Dunlop, Scott" <[EMAIL PROTECTED]>
zum Thema [REBOL] Objects, Inheritance and Barking Up Wrong Trees?:
> I am currently trying to determine the best way to override an object
> method; at the moment, I've been doing the obvious thing, copying the
> function into a new binding:
> ss-histfield: stylize [
> histfield: field with [
> feel: make feel [
> old-engage: get 'engage
> engage: func [face act event index][
> switch/default act [
> ; << Special Case Code Here >>
> ] [
> old-engage face act event index
> ]
> ]
> ]
> ]
> ]
> While this works, it is more brittle than I would like, since the
old-engage
> binding isn't private to histfield's feel, and could collide with a
child
> trying to do a similar thing, or revisions to the field feel. Does
anyone
> have a simpler / better solution for doing this?
> Btw, I am aware that there is probably another way to override
feel/engage,
> but this is one of two sticking points that my Python-oriented mind
tends to
> get hung up on. The other is my addiction to Dictionaries.
Ugly, and you cannot use [()]'s in your top-level-code, but
with 'compose you can do:
>> a: context[
[ b: func[a][probe a]
[ ]
>> c: make a[
[ b: func[a]compose/deep[
[ (second :b)
[ probe a * a
[ ]
[ ]
>> a/b 123
123
== 123
>> c/b 123
123
15129
== 15129
Volker
> --Scott.
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