[Tutor] friday night entertainment (a generator)

[Gregor Lingl]

Hi,

I just wrote a generator which generates
all the r-permutations of n distict objects,
(this most probably is an old soup, newly cooked up -
or a wheel reinvented):

def perms(n,r,result=()):
    if r == 0:
        yield result
    for element in n:
        t = n[:]
        t.remove(element)
        for perm in perms(t,r-1,result+(element,)):
            yield perm
           
 >>> for p in perms(range(4),2):
    print p

   
(0, 1)
(0, 2)
(0, 3)
(1, 0)
(1, 2)
(1, 3)
(2, 0)
(2, 1)
(2, 3)
(3, 0)
(3, 1)
(3, 2)
 >>>

Do any amendments (concerning efficiency and/or elegance)
come to your mind?

Any hints or suggestions are highly appreciated

Gregor