On Jul 10, 9:46 pm, ssecorp <[EMAIL PROTECTED]> wrote: > >>> def mod(x,y): > > return x.append(y) > append adds y to list x and returns None, which is then returned by mod.
> > > >>> mod([1,2],3) > >>> k=[1,2,3] > >>> k > [1, 2, 3] > >>> l = mod(k,4) 4 has been appended to list k and mod has returned None, so l is now None. > >>> l > >>> k > [1, 2, 3, 4] > >>> l > >>> k==l > False Because k is [1, 2, 3, 4] and l is None. > >>> mod(k,5) > >>> k > [1, 2, 3, 4, 5] > >>> mod(l,4) > > Traceback (most recent call last): > File "<pyshell#29>", line 1, in <module> > mod(l,4) > File "<pyshell#18>", line 2, in mod > return x.append(y) > AttributeError: 'NoneType' object has no attribute 'append' > l is None, not a list, so it complains! > >>> l > >>> l=k > >>> l > [1, 2, 3, 4, 5] > >>> i=mod(k,1) > >>> i > > same stuff but i dont find this intuitive. It's usual for methods which modify to return None. -- http://mail.python.org/mailman/listinfo/python-list
