Forwarding to the list.
---------- Forwarded message ---------- From: W W <[EMAIL PROTECTED]> Date: Tue, May 20, 2008 at 12:31 PM Subject: Re: [Tutor] timed functions? Timeouts? To: Kent Johnson <[EMAIL PROTECTED]> On Tue, May 20, 2008 at 7:18 AM, Kent Johnson <[EMAIL PROTECTED]> wrote: >> Then I'm a little confused by the * and ** - they look just like the >> pointer and pointer to a pointer in C++, but do they perform the same >> function in python? > > No, these are not pointers, they allow passing arbitrary lists and > dicts of arguments. I don't know of a good writeup of this syntax; > here are some pointers: > http://bytes.com/forum/thread25464.html Ahhh, now I see (I think). Here's what I've discovered. The * unpacks the list into a tuple, creating a "new" variable that as far as I can tell, dies when the function ends. ** creates a copy of the dictionary, rather than passing the actual dictionary, so it's possible to operate on it, leaving the original dict intact. Neither value is actually considered an argument: >>> def SomeFunction(**foo): ... print foo ... >>> mydict = {'abc':123} >>> SomeFunction(mydict) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: SomeFunction() takes exactly 0 arguments (1 given) >>> SomeFunction(**mydict) {'abc': 123} ---- Using a list without * doesn't create an error at all, instead it yields results I didn't expect: >>> def SomeFunction(*foo): ... print foo ... >>> mylist = ['a', 'b', 'c'] >>> SomeFunction(mylist) (['a', 'b', 'c'],) ---- Specifically, it doesn't unpack the list, it just packs the list into a tuple. With a little more experimentation I've discovered that you can manually enter data, instead of using a list: >>> def another_function(*foo): ... print foo ... >>> another_function('hello', 'spork', 1,2,3) ('hello', 'spork', 1, 2, 3) Now I just have to figure out exactly how thread/threading uses these tuples! Thanks again! -Wayne -- To be considered stupid and to be told so is more painful than being called gluttonous, mendacious, violent, lascivious, lazy, cowardly: every weakness, every vice, has found its defenders, its rhetoric, its ennoblement and exaltation, but stupidity hasn't. - Primo Levi _______________________________________________ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
