Accessing next/prev element while for looping

Paul Rubin http
Mon Dec 19 09:35:17 CET 2005


Paul Rubin <http://phr.cx@NOSPAM.invalid> writes:
>    elts = iter(myarray)
>    prev,cur,next = elts.next(),elts.next(),elts.next()
>    for next2 in elts:
>       do_something_with (prev, cur, next)
>       prev,cur,next = cur, next, next2
> 
> Of course these fail when there's less than 3 elements.

Ehh, too clever for my own good.  This fails with exactly 3 elements.
It was a "shortened" version of 

    elts = iter(myarray)
    prev,cur,next = elts.next(),elts.next(),elts.next()
    try:
      while True:
         do_something_with (prev, cur, next)
         prev,cur,next = cur, next, elts.next()
    except StopIteration: pass

which is messy, and which could get confused by do_something_with...
raising StopIteration for some reason.



More information about the Python-list mailing list