On 2007-04-26, Steven Howe <[EMAIL PROTECTED]> wrote: > [EMAIL PROTECTED] wrote: >>> Well, why do some things in the library have to be functions, >>> and other things have to be class methods? > > Perhaps because some things are more naturally function like? > For 'instance' (pardon the pun), functions shouldn't retain > data. They perform an operation, return data and quit. While > retaining data is a feature of an class/instance.
Functions do retain data. Classes and instances are just a convenient notation. ;) >>> def funmaker(f, x): ... return lambda: f(x) ... >>> d = funmaker(int, 10) >>> d() 10 In addition, all functions in Python have data members, too. >>> d.label = "d" >>> d.label 'd' Python's scoping rules make certain kinds of functional idioms hard to use, though. I'm not sure how to get the following to work in Python using functions: >>> def account(s): ... b = s ... def add(a): ... b += a ... def balance(): ... return b ... return add, balance ... >>> add, balance = account(100) >>> balance() 100 >>> add(5) Traceback (most recent call last): File "<stdin>", line 1, in ? File "<stdin>", line 4, in add UnboundLocalError: local variable 'b' referenced before assignment Anyhow, it doesn't work, but you can see how closely it resembles a class definition. > And before someone get's all technical, I know everything in > Python is an 'object' even None, which implies class, or is it > the other way around? Classes are just objects like everything else. -- Neil Cerutti Bach's death is attributed to the end of the Baroque era. --Music Lit Essay -- http://mail.python.org/mailman/listinfo/python-list
