define 'in' operator on lists

[Duncan Booth]

..:: sjf ::.. wrote:

> I want to define 'in' operator (or any "magic" function) on list which 
> returns True value if all of list (i.e. _list) elements appears in other 
> list (i.e. L) in the same order and False otherwise. 

How about:

>>> def containedinsequence(short, long):
	ilong = iter(long)
	for s in short:
	    for l in ilong:
		if s==l:
		    break
	    else:
		return False # ran out of long list
	return True

>>> L = [1, 2, 3, 4, 5, 6]
>>> containedinsequence([3, 4, 6], L)
True
>>> containedinsequence([3, 4, 7], L)
False
>>> containedinsequence([3, 4, 3], L)
False
>>> containedinsequence([], L)
True
>>>