recursion depth problem

[proctor]

On Apr 22, 7:34 pm, Steven Bethard <steven.beth... at gmail.com> wrote:
> proctor wrote:
> > On Apr 22, 2:06 pm, Steven Bethard <steven.beth... at gmail.com> wrote:
> >> proctor wrote:
> >>> On Apr 22, 1:24 pm, Michael Bentley <mich... at jedimindworks.com> wrote:
> >>>> On Apr 22, 2007, at 1:49 PM, proctor wrote:
> >>>>> i have a small function which mimics binary counting.  it runs fine as
> >>>>> long as the input is not too long, but if i give it input longer than
> >>>>> 8 characters it gives
> >>>>> RuntimeError: maximum recursion depth exceeded in cmp
> >>>>> i'm not too sure what i am doing improperly.  is there really a lot of
> >>>>> recursion in this code?
> >>>>> ==================
> >>>>> import sys
> >>>>> def ch4(item, n=0):
> >>>>>    if n < len(item):
> >>>>>            if item[n] == '0':
> >>>>>                    item[n] = '1'
> >>>>>                    print ''.join(item)
> >>>>>                    ch4(item)
> >>>>>            elif item[n] == '1':
> >>>>>                    item[n] = '0'
> >>>>>                    ch4(item, n+1)
> >>>>> ch4(list(sys.argv[1]))
> >>>>> ==================
> >>>> Yes.  There really is *that* much recursion in that code.  502 levels
> >>>> with input length of 8 characters, 1013 with 9 characters, 2035 with
> >>>> 10 characters...  There's a pattern there ;-)
> >>> ok, thanks michael!
> >>> is there a way to avoid it here?  how could i write this better, (if
> >>> at all)?
> >> Google for permutation-like recipies:
>
> >>      http://www.google.com/search?q=Python+permutations
>
> >> Use the code from the first hit::
>
> >>      >>> for x in xselections('01', 8):
> >>      ...     print ''.join(x)
> >>      ...
> >>      00000000
> >>      00000001
> >>      00000010
> >>      ...
> >>      11111101
> >>      11111110
> >>      11111111
>
> >> Explaining to your teacher why your code uses generators when you
> >> haven't been taught them yet is left as an exercise to the reader. ;-)
>
> >> STeVe
>
> > this is really nice, thanks steve.  much slicker than my code.
>
> > for interest sake:  is my method unredeemable?
>
> Let's just say that I don't currently see an obvious way of redeeming
> it. ;-)
>
> STeVe

lol.  okay.

proctor.