keakon <kea...@gmail.com> wrote: > def h2(x=[]): > y = x > y.append(1) > return y + []
> h2() is about 42 times slower than h2([]), but h() is a litter faster > than h([]). Are you aware that 'y = x' _doesn't_ make a copy of [], that it actually points to the same list as x? My guess is that the slowdown you're seeing is due to the increasing size of x _per timing iteration_. h2([]) will pass a new list each time, while h2() will append to the same list _every_ time. The difference between h & h2 is due to the concatenation of a new list to the built one: the longer the default list grows, the longer this will take, as extending a list takes O(k) time, with k being the number of elements. -- http://mail.python.org/mailman/listinfo/python-list
