Do we have a iterator pattern in newlisp like the one in python?
>>> lst = [3, 2, 1]
>>> s = iter(lst)
>>> s
<listiterator object at 0xb741e0cc>
>>> s.next()
3
>>> s.next()
2
>>> s.next()
1
>>> s.next()
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
StopIteration
Here 's' is an object AND not a copy of the original list.
You can fake it with pop ;o)
To remove a items from the head of the list:
(setq s '(3 2 1))
(pop s) ;-> 3
(pop s) ;-> 2
(pop s) ;-> 1
(pop s) ;-> nil
To remove a items from the end of the list:
(setq s '(3 2 1))
(pop s -1) ;-> 1
(pop s -1) ;-> 2
(pop s -1) ;-> 3
(pop s -1) ;-> nil
-- xytroxon
Further elaboration on xytroxon reply:
(context 'next)
(setq seenSymbols '())
(define-macro (next:next aList)
(unless (ref (string aList) next:seenSymbols)
(push (list (string aList) (copy (eval aList))) next:seenSymbols))
(pop (next:seenSymbols (first (ref (string aList) next:seenSymbols)) 1))
)
Exercises to the reader:
1. optionally allow to re-copy symbol contents into
2. convert to object like form