On 2007-02-14, Farshid Lashkari <[EMAIL PROTECTED]> wrote: > Szabolcs Nagy wrote: >>>>> L=[1] >>>>> L.extend((1,)) >>>>> L >> [1, 1] > > Are list.extend() and list concatenation supposed to behave > differently? I always thought concatenation was just shorthand > for calling extend().
They are different. list.extend() mutates the list, returning None, while the + operator returns a new, concatenated list. += on the other hand works very similarly to list.extend(). However: >>> [1, 2].extend([3]) >>> [1, 2] += [3] SyntaxError: augmented assign to list literal or comprehension not possible > It seems like the '+' operator for lists should accept any > iterable for the right side argument to be consistent with > extend() and the '+=' operator. += will only perform the operation in place "whenever possible", so there are objects for which a conversion to .extend wouldn't work, and you'd get an actual call of the + operation followed by the assignment operation. -- Neil Cerutti I don't know what to expect right now, but we as players have to do what we've got to do to make sure that the pot is spread equally. --Jim Jackson -- http://mail.python.org/mailman/listinfo/python-list
