At 10:57 22.10.2003 -0700, Guido van Rossum wrote:
def tee(iterable): "Return two independent iterators from a single iterable" data = {} cnt = 0 def gen(next): global* cnt dpop = data.pop for i in count(): if i == cnt: item = data[i] = next() cnt += 1 else: item = dpop(i) yield item next = iter(iterable).next return (gen(next), gen(next))
which is IMO more readable.
it's a subtle piece of code. I wouldn't mind a more structured syntax with both the outer function declaring that is ok for some inner function to rebind some of its locals, and the inner function declaring that a local is coming from an outer scope: def tee(iterable): "Return two independent iterators from a single iterable" data = {} # cnt = 0 here would be ok share cnt = 0: # the assignment is opt, # inner functions in the suite can rebind cnt def gen(next): use cnt # OR outer cnt dpop = data.pop for i in count(): if i == cnt: item = data[i] = next() cnt += 1 else: item = dpop(i) yield item # cnt = 0 here would be ok next = iter(iterable).next return (gen(next), gen(next)) yes it's heavy and unpythonic, but it makes very clear that something special is going on with cnt. no time to add anything else to the thread. regards.