Henry
On 2011-05-29, at 5:47 , Wolfgang Rohdewald wrote: > On Sonntag 29 Mai 2011, Henry Olders wrote: >> It seems that in Python, a variable inside a function is >> global unless it's assigned. > > no, they are local > >> I would have thought that a function parameter would >> automatically be considered local to the function. It doesn't >> make sense to me to pass a global to a function as a >> parameter. > > it is local. But consider what you actually passed: > You did not pass a copy of the list but the list itself. > You could also say you passed a reference to the list. > All python variables only hold a pointer (the id) to > an object. This object has a reference count and is > automatically deleted when there are no more references > to it. > > If you want a local copy of the list you can either > do what you called being ugly or do just that within > the function itself - which I think is cleaner and > only required once. > > def fnc2(c): > c = c[:] > c[1] = 'having' > return c Thank you, Wolfgang. That certainly works, but to me it is still a workaround to deal with the consequence of a particular decision. From my perspective, a function parameter should be considered as having been assigned (although the exact assignment will not be known until runtime), and as an assigned variable, it should be considered local. Henry -- http://mail.python.org/mailman/listinfo/python-list
