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NNTP-Posting-Date: Wed, 07 Nov 2012 07:42:18 -0600
From: Chris Hinsley <chris.hinsley@gmail.com>
Newsgroups: comp.lang.forth
Date: Wed, 7 Nov 2012 13:42:18 +0000
Message-ID: <2012110713421835115-chrishinsley@gmailcom>
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Subject: Genral advise and comments on callback style words
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Xref: csiph.com comp.lang.forth:17115

Folks I have implamented an Amiga style double linked list words set a 
few days back and I have an emueration word as follows:

\ ( u xt lh -- ln | 0)
\ xt api is ( u ln lh -- ln | 0 )
: LISTHEAD-ENUMERATE-FORWARDS
	0 >R
	DUP LISTHEAD-GET-HEAD DUP
	BEGIN
		NIP DUP LISTNODE-GET-SUCC
		DUP
	WHILE
		4 PICK 2 PICK 4 PICK
		6 PICK EXECUTE DUP R!
	UNTIL THEN
	2DROP 2DROP DROP
	R>
;

This scans down the list until either it hits the end, or the callback 
for each node returns a value other than 0, that value is returned and 
the scan stops if it isn't 0 !

I'd like comments and advice on techniuqe, paticularly for things like 
the PICK stuff that gathers paramaters for each callback, and the use 
of the return stack for the returned value. Or if you just plain think 
I could code this a better way !

I'm not wanting to be pointed to "the novice package", thank you, but 
want this API as stated ! ;)

Regards all

Chris