With all due respect, let me suggest that we check out code snippets
bofore posting them to the list. The suggested code is extremely
broken:
Copyright 2000 REBOL Technologies. All rights reserved.
>> a: make block! 1 ; could be make hash! for faster key search
== []
>> a/append [Key Value]
** Script Error: Invalid path value: append.
** Where: a/append [Key Value]
>> TheValue: a/select Key
** Script Error: Invalid path value: select.
** Where: TheValue: a/select Key
A working variation is:
>> a: make block! 1
== []
>> append a [Key Value]
== [Key Value]
>> select a 'Key
== Value
>>
Note that the use of bare words in the append means that the target
passed to select must be a lit-word! or an expression that EVALUATES
to the key word:
>> foo: 'Key
== Key
>> select a foo
== Value
>> select a first [Key]
== Value
>> select a reduce ['Key]
== Value
That requirement may be a bit unobvious/tedious.
My big problem with using append and select with a block as an
implementation of associative arrays is that the keys and values are
not distinguished. Consider the imaginary product descriptions below:
>> appliance1: ["type" "tv" "screen" "b&w" "size" 19 "color" "woodgrain"]
== ["type" "tv" "screen" "b&w" "size" 19 "color" "woodgrain"]
>> appliance2: ["type" "tv" "screen" "color" "size" 21 "color" "charcoal"]
== ["type" "tv" "screen" "color" "size" 21 "color" "charcoal"]
Now let's look up some properties of these appliances:
>> select appliance1 "color"
== "woodgrain"
>> select appliance2 "color"
== "size"
>>
Since keys and values are all just in a big pile, there's no guarantee
that a select or find using "color" as a key won't accidentally hit
an occurrence of "color" as a value instead (giving me the next key as
the result of select ).
I'll follow up with an email containing a proposed implementation for
folks on the list to critique.
-jn-
[EMAIL PROTECTED] wrote:
>
> >Has any one made an associative arrary in Rebol? Something like:
> >a/Associate Key Value
> >TheValue: a/find Key
> >It would be nice to show this to people used to using associative
> >arrays, that Rebol can do so as well.
> >
> >Andrew Martin
>
> a: make block! 1 ; could be make hash! for faster key search
> a/append [Key Value]
> TheValue: a/select Key
>
> That should make it ?
>
> DK.
--
; Joel Neely [EMAIL PROTECTED] 901-263-4460 38017/HKA/9677
REBOL [] print to-string debase/64 decompress #{
789C0BCE0BAB4A7176CA48CAB53448740FABF474F3720BCC
B6F4F574CFC888342AC949CE74B50500E1710C0C24000000}
