So I'm reading through the Python Tutorial (on chapter 5 now) and am so far thoroughly enjoying myself. I've run into a bit of a hitch, though. A peice of example code showed this:

>>> for i in reversed(xrange(1,10,2)):
...   print i
...  

and it should work just peachy. But I get this error when I try to run it through:

Traceback (most recent call last):
  File "", line 1, in ?
NameError: name 'reversed' is not defined  

Is reversed() perhaps in a module of some sort that I have to import? Any help would be much appreciated. [edited by - Drevay on January 19, 2004 12:06:31 AM]

reversed() is in Python 2.4.

Python 2.4 isn''t even out yet, and this is the Python 2.3.3 tutorial I''m on.

You think they''d put in something that would only work in a future release? I doubt it.

I mean, sort() says the same thing if you don''t use it properly, but I can''t seem to get help on reversed().

I tried help(list.reversed) but it seems to come up with nothing.

What module would the reversed() function be from?

Perhaps it is in 2.4 only... Odd..

def reversed(x):   return x[::-1] 

[edited by - Fruny on January 19, 2004 12:59:23 AM]

Thanks, Fruny. Although I was wondering since the Tutorial treated it like a built in function ("This is how you blah blah blah"). It listed enumeration and iteritems along with it.

:S

quote: Original post by Drevay
So I''m reading through the Python Tutorial (on chapter 5 now) and am so far thoroughly enjoying myself.

I''ve run into a bit of a hitch, though. A peice of example code showed this:

>>> for i in reversed(xrange(1,10,2)):...   print i...   

and it should work just peachy.

Where did you get that code from? I don''t see it anywhere in the Python Tutorial. reversed() is due to be added as a built-in, as described in PEP 322.

Oh, well it is - I downloaded Python a few days ago, it''s in chapter 5, look there.

Odd that they''d put that in there...

Well, now I''m satisfied.

That was bugging the hell out of me!

Very useful note from Python tutorial (scroll up a line).

[Edit: So useful I made it a clicky!]

[edited by - Oluseyi on January 20, 2004 1:49:46 PM]

Note that the overhead of calling Fruny''s reversed function can cause a performance degradation. FAQ.