inner sublist positions ?

[Bernard A.]

hello, 

while trying to play with generator, i was looking for an idea to get
the position of a inner list inside another one, here is my first idea
:
- first find position of first inner element, 
- and then see if the slice starting from here is equal to the inner
->

>>> def subPositions(alist, innerlist):
	if innerlist == []:
		return
	first, start = innerlist[0], 0
	while 1:
		try:
			p = alist[start:].index(first)
		except ValueError:
			break # or should i better use return ?
		start = start + p		
		if alist[start: start + len(innerlist)] == innerlist:
			yield start, start + len(innerlist)
		start += 1

		
>>> list(subPositions(range(5) + range(5), [2,3]))
[(2, 4), (7, 9)]

maybe have you some better / faster ideas / implementations ? or even
a more pythonic to help me learning that

game2 :) => how can i imagine a way to have the inclusion test rather
be a test upon a regular expression ? i mean instead of checking for
an inner list, rather checking for an "inner regular expression"
matching upon consecutives items of a list ? (btw it isn't still not
really clear in my own mind, but it looks like ideas from here are
always clever one, it may help :)

best,