On 2007-12-10, Hrvoje Niksic <[EMAIL PROTECTED]> wrote: > Neil Cerutti <[EMAIL PROTECTED]> writes: > >> Anyhow, implementing linked lists in Python is not challenging, but >> they don't work well with Python iterators, which aren't suitable >> for a linked list's purposes--so you have to give up the happy-joy >> for loop syntax in favor of Python's frowny-sad while loops. > > With the help of generators, it is trivial to turn a frowny loop into > a happy one: > > class Node: > def __init__(self): > self.next = None > # attach data to the node as needed, and use "next" to refer > # to the next node. > > def __iter__(self): > node = self > while 1: > yield node > node = node.next > if node is None: > break > > def linkify(it): > """Turn a Python iterable into a linked list.""" > head = prev = None > for elem in it: > node = Node() > node.data = elem > if prev is None: > head = node > else: > prev.next = node > prev = node > return head > > # iterate over a linked list using 'for': > >>>> linkedlist = linkify([1, 2, 3]) >>>> for n in linkedlist: > ... print n.data > ... > 1 > 2 > 3 > > Correctly handling empty lists is left as an excercise for the > reader.
It was providing the ability to mutate the list using an iterator as a node reference that I alleged rendered linked lists a bit awkward in Python syntax. The discussion yielded a couple of solutions, though. -- Neil Cerutti And now the sequence of events in no particular order. --Dan Rather -- http://mail.python.org/mailman/listinfo/python-list
