Hi Rodney,
I believe REBOL makes a new copy of functions for each derived object.
Let me introduce the players: A root object o, a function f, and a derived
object p:
>> o: make object! [f: func [] [print "a"] ]
>> p: make o []
At this point the two objects are look-alikes:
>> probe o
make object! [
f: func [][print "a"]
]
>> probe p
make object! [
f: func [][print "a"]
]
Let us replace the string "a" by the string "b" in p's function f
>> change at second get in p 'f 2 "b"
== []
Were we successful?
>> probe p
make object! [
f: func [][print "b"]
]
Yes. Was the function f in the parent object o also modified?
>> probe o
make object! [
f: func [][print "a"]
]
No!
Apparently modifications to the inherited function f in p do not propagate
to the f function in the parent object o, ergo the two functions are
independent of each other.
At 02:10 PM 9/14/00 -0700, you wrote:
>Great stuff from both of you - I am thinking of changing my
>INI file handling code to one of these methods (where I have
>a hash of hashes so that a section value is really itself an
>associative array).
>
>But Elan, what do you mean when you say that there is a
>problem with function code duplication using the object approach?
>I haven't used a lot of Rebol objects yet, but my OOP experience
>tells me (yes I know I'm supposed to forget it about that!) that
>there is only one instance of code for all objects based on a
>base template.
>
>TIA,
>
>Rodney
>
>
>
>-----Original Message-----
>From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]
>Sent: Thursday, September 14, 2000 1:38 PM
>To: [EMAIL PROTECTED]
>Subject: [REBOL] Associative data store Re:
>
>
>Hi Joel,
>
>Nice.
>
>you wrote:
>>Critiques and comments welcome!
>
>With respect to the line:
>> new: func [/local r] [r: make assoc [] r/clear r]
>
>I think it would be safer to use self instead of assoc
>
>new: func [/local r] [r: make self [] r/clear r]
> ^^^^
>2. An alternative:
>
>assoc: [keys [] values []]
>is-assoc?: func [assoc [block!]] [
> all [equal? length? assoc 4 find assoc 'keys find assoc 'values]
>]
>contains-key?: func [assoc [block!] key [any-type!] ] [
> all [is-assoc? assoc find assoc/keys key]
>]
>assoc-add: func [assoc [block!] candidates [block!] /local found] [
> if is-assoc? assoc [
> foreach [key value] candidates [
> either found: contains-key? assoc key [
> insert at assoc/values index? found value
> ][
> insert assoc/keys key
> insert assoc/values value
> ]
> ]
> return true
> ]
> return false
>]
>assoc-get: func [assoc [block!] key [any-type!] /local found] [
> if found: contains-key? assoc key [
> return pick assoc/values index? found
> ]
> return none
>]
>
>>> phonelist: copy/deep assoc
>== [keys [] values []]
>>> assoc-add phonelist [Bill "555-1111"]
>== true
>>> assoc-add phonelist [Al "555-2222"]
>== true
>>> assoc-add phonelist [George "555-3333"]
>== true
>>> assoc-add phonelist [Dick "555-4444"]
>== true
>>> assoc-add phonelist [Jane "555-3322" Judy "555-2233"]
>== true
>>> assoc-get phonelist 'Bill
>== "555-1111"
>>> assoc-get phonelist 'Dick
>== "555-4444"
>>> assoc-get phonelist 'George
>== "555-3333"
>>> assoc-get phonelist 'Jane
>== "555-3322"
>>> assoc-get phonelist 'Judy
>== "555-2233"
>>> assoc-get phonelist 'Al
>== "555-2222"
>
>>> foreach who sort copy phonelist/keys [print [who assoc-get phonelist
>who]]
>Al 555-2222
>Bill 555-1111
>Dick 555-4444
>George 555-3333
>Jane 555-3322
>Judy 555-2233
>
>Looks to me like it accomplishes pretty much the same thing
>
>> separation of key/value spaces
>
>without the additional overhead of an object (function code duplication for
>each list). In addition I see the advantage of being able to effortlessly
>add multiple items by including them in a block (batch adding ;-).
>
>At 04:01 PM 9/14/00 -0500, you wrote:
>>The proposed implementation below addresses separation of key/value
>>spaces and tries to take advantage of REBOL built-ins for performance
>>wherever feasible. Critiques and comments welcome!
>>
>>-jn-
>>
>>===============(begin code listing)==================
>>REBOL [
>> Title: "Minimal Associative Data Store"
>> File: %assoc.r
>> Date: 14-Sep-2000
>> Author: "Joel Neely"
>> Purpose: {
>> Quick, minimal implementation of a data store that
>> associates arbitrary values with (string!) keys.
>> }
>>]
>>
>>assoc: make object! [
>> _keys: copy []
>> _vals: copy []
>> clear: func [] [_keys: copy [] _vals: copy []]
>> clear?: func [] [empty? head _keys]
>> count?: func [] [length? _keys]
>> new: func [/local r] [r: make assoc [] r/clear r]
>> put: func [k [string!] v [any-type!] /local p] [
>> either none? p: find _keys k [
>> append _keys k
>> append _vals v
>> ][
>> change at _vals index? p v
>> ]
>> v
>> ]
>> get: func [k [string!] /local p] [
>> either none? p: find _keys k [
>> none
>> ][
>> pick _vals index? p
>> ]
>> ]
>> keys: func [] [copy _keys]
>>]
>>=================(end code listing)==================
>>
>>This (minimal) implementation can be used as follows:
>>
>>=================(begin transcript)==================
>>>> do %assoc.r
>>>> phonelist: assoc/new
>>>> phonelist/clear?
>>== true
>>>> phonelist/put "Bill" "555-1111"
>>== "555-1111"
>>>> phonelist/put "Al" "555-2222"
>>== "555-2222"
>>>> phonelist/put "George" "555-3333"
>>== "555-3333"
>>>> phonelist/put "Dick" "555-4444"
>>== "555-4444"
>>>> phonelist/get "Al"
>>== "555-2222"
>>>> phonelist/count?
>>== 4
>>>> phonelist/keys
>>== ["Bill" "Al" "George" "Dick"]
>>>> foreach who phonelist/keys [print [who "^-" phonelist/get who]]
>>Bill 555-1111
>>Al 555-2222
>>George 555-3333
>>Dick 555-4444
>>>> foreach who sort phonelist/keys [print [who "^-" phonelist/get who]]
>>Al 555-2222
>>Bill 555-1111
>>Dick 555-4444
>>George 555-3333
>>>> privatelist: phonelist/new
>>>> privatelist/count?
>>== 0
>>>>
>>>> foreach who head reverse sort phonelist/keys [
>>[ print [who "^-" phonelist/get who]
>>[ ]
>>George 555-3333
>>Dick 555-4444
>>Bill 555-1111
>>Al 555-2222
>>>>==================(end transcript)===================
>>
>>Enjoy!
>>
>>-jn-
>>
>>--
>>; Joel Neely [EMAIL PROTECTED] 901-263-4460 38017/HKA/9677
>>REBOL [] print to-string debase/64 decompress #{
>> 789C0BCE0BAB4A7176CA48CAB53448740FABF474F3720BCC
>> B6F4F574CFC888342AC949CE74B50500E1710C0C24000000}
>>
>>
>>
>
>;- Elan [ : - ) ]
> author of REBOL: THE OFFICIAL GUIDE
> REBOL Press: The Official Source for REBOL Books
> http://www.REBOLpress.com
> visit me at http://www.TechScribe.com
>
>
>
;- Elan [ : - ) ]
author of REBOL: THE OFFICIAL GUIDE
REBOL Press: The Official Source for REBOL Books
http://www.REBOLpress.com
visit me at http://www.TechScribe.com
