On Fri, Apr 11, 2008 at 12:06 PM, Brad Miller <report@bugs.python.org> wrote:

>  Our use of range in the first few classes is exactly for iteration
>  purposes, but I do not like students to have to have too many mysteries.
>  So I always have liked to show that range(10) simply produces a sequence

.. but it does not in 3.x and your patch does not change that.
Instead, range(10) produces range(0,10) and I don't see anything
mysterious here.

>  of integers.  In Python 3.0 range returns a mysterious iteration object.
>  No thanks.  My proposal was to provide a more user friendly
>  implementation of the str method for this new range object that would
>  allow the user to see the sequence.  I like Python because it is so easy
>  to start up a shell and poke around and see what things are.
>

Maybe you should try it with some of your students first.  Note that
you can customize the way results are printed on the console with
sys.displayhook.   I fail to see how <0, 1, ... 9> is less mysterious
than range(0,10), particularly combined with the fact that print
representation is different from console display.  I think <0, 1, ...
9> will confuse more students than it will help.

>  I have no problem, introducing list(range(10)) in week 3 when I start
>  talking about lists, and I like list comprehensions of that purpose too.
>

Why would you want to talk about loops before talking about lists?
Python is not C.  In many cases for x in some_list or for i,x in
enumerate(some_list) is a better construct than for i in range(..).

>  Again, what I do not like is that things that used to be very easy for
>  students to get a conceptual handle on are now more difficult in 3.0.

With your proposed <..> display students will be getting a wrong
concept, thinking that <1, 2, 3> is yet another container in addition
to (1,2,3), [1,2,3] and {1,2,3}.

>  - range is one example the dict_keys and dict_values objects are another
>  example.  dict_keys et. al. are much easier to deal with since I've
>  already covered lists and the list() function by the time I get there.
>

IMHO list function is simpler than the print function, particularly in
cases when it does not print what you enter.

>  BTW, I think  we must have very different teaching styles as I would
>  never introduce something as mysterious as list(_) on the first day of
>  class.  I'd be happy to continue our discussion of teaching philosophy
>  but I doubt that this is the right forum.
>

Your students are probably older than mine.  I don't teach, but I
introduced my son to python when he was 10.  He is 12 now and is quite
comfortable using python as a calculator (computing 2**1000 in python
what quite an experience!)  Explaining that _ stands for the value
that just printed was easier than introducing variables (as in
x=range(10); list(x)).