Re: Creating and using arrays - again

In article
<alpine.OSX.1.00.0803211430350.2044@[EMAIL PROTECTED]
>,
Duke Normandin  <dukeofperl@[EMAIL PROTECTED]
> wrote:
>On Fri, 21 Mar 2008, Elizabeth D Rather wrote:
>
>>
>>
>> Duke Normandin wrote:
>> > On Fri, 21 Mar 2008, Elizabeth D Rather wrote:
>> ...
>> >
>> > > A more Forthish approach would be:
>> > >
>> > > : ARRAY ( n -- )   CREATE  CELLS ALLOT
>> > >    DOES> ( i -- i-addr )   CELLS + ;
>> >
>> > I'm just now clueing in on Forth's 'double-barrel' / 'delayed-duet'
>> > capability of CREATE / DOES>
>>
>> The best way to think about it is that the part before the DOES>
specifies a
>> class of words with a shared defining behavior.  The part after the
DOES>
>> defines the shared behavior of all instances of this class of
definitions.
>
>I got it! Every "array" incarnated using ARRAY will all be created using
>the "defining words". Everyone of these "arrays" will execute the words
>following DOES> when called with the appropriate value in TOS.
>

And note that this is the same idea as having cl*****.
[This was in Forth 15 years before most people had heard of cl*****!]
A class defines a data structure with common behaviour. So the "class"
ARRAY can be used to have arrays. ARRAY APE gives you an "object" APE.
The difference with "real" cl***** is that you don't have named
methods, the only thing you can do is say ``APE'' and the default
behaviour (of DOES> ) happens.

You can always help yourself out by using >BODY though. Look it up!

>Duke Normandin

Groetjes Albert

--
-- 
Albert van der Horst, UTRECHT,THE NETHERLANDS
Economic growth -- like all pyramid schemes -- ultimately falters.
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