On Wed, Dec 3, 2008 at 9:18 PM, <[EMAIL PROTECTED]> wrote: > I just came across http://www.perl.com/pub/a/2002/05/29/closure.html > and wanted to try the "canonical example of closures" in Python. I > came up with the following, but it fails: > > ####################### > #!/usr/bin/env python >
Depending on your version of Python, you need to do either (A) or (B). (A) requires Python 3.0 IIRC. > def make_counter(start_num): > start = start_num (B) replace prev line with: start = [start_num] > def counter(): (A) add: nonlocal start > start += 1 (B) replace prev line with: start[0] += 1 > return counter > > from_ten = make_counter(10) > from_three = make_counter(3) > > print from_ten() # 10 > print from_ten() # 11 > print from_three() # 3 > print from_ten() # 12 > print from_three() # 4 > #################### > > The error message is: "UnboundLocalError: local variable 'start' > referenced before assignment". The same thing happens if I omit start > and just use start_num directly. See http://www.python.org/dev/peps/pep-3104/ for more info. Cheers, Chris -- Follow the path of the Iguana... http://rebertia.com > > How can I do it in Python? > -- > http://mail.python.org/mailman/listinfo/python-list > -- http://mail.python.org/mailman/listinfo/python-list
