PEP 276 -- What else could iter(5) mean?

[logistix]

Of course your example makes since, but look at this more complex one:

def functionInMyModule(lst = []):
    #assumes we recieve a list, no type checking
    for i in lst:
        performSomeOperation(i)

-------------------------------------------------
end user script
-------------------------------------------------

import myModule

x = eval( raw_input("Enter some numbers") )

myModule.functionInMyModule(x)


When you run the script, a user is prompted for some numbers.  If they enter
1,2,3,4,5, a tuple of (1,2,3,4,5) is created that can then be iterated.  If
they just enter 5, then they probably only want to perform this operation on
5, but when functionInMyModule() is called, the results will be identical to
the first example, when you really want it to throw an error or create a
tuple of (5).

This isn't necessarily the best example, but it's situations like this that
make the proposed syntax unclear.  In practice, there are alot of for:
operations that are beina applied to an arbitrary python objects that may or
may not be an int.  In these cases PEP 276 would result in unexpected
behaviour.

-

"Cromwell, Jeremy" <jcromwell at ciena.com> wrote in message
news:mailman.1015116845.8928.python-list at python.org...
> If python was to allow "for i in 5:", is there any other meaning that
would
> be appropriate besides the one detailed in PEP 276?
>
> Without trotting out ugly examples, it is cleaner than many of the current
> features in python.  I'm still a relative newbie, but I remember it being
a
> bit jarring to need to use range() just to iterate through numbers.
>
> It's so simple to explain and understand, that I doubt that it would be
> confusing.  Here's my clumsy rewording of the tutorial:
>
> 4.3 For x in integer, and the range() Function
> When given an integer rather than a sequence, the for statement iterates
> over the numbers from 0 up to (but not including) the given number:
>
> >>> for i in 3:
> ...     print i, i*3
> 0, 0
> 1, 3
> 2, 6
>
> The given end point is never part of the generated list; for x in 10
> iterates through a list of 10 values, exactly the legal indices for items
of
> a sequence of length 10.
>
> To iterate over the indices of a sequence, use len() as follows:
>
> >>> a = ['Mary', 'had', 'a', 'little', 'lamb']
> >>> for i in len(a):
> ...     print i, a[i]
> ...
> 0 Mary
> 1 had
> 2 a
> 3 little
> 4 lamb
>
>
> If you do need to iterate over a more complex sequence of numbers, the
> built-in function range() comes in handy. It generates lists containing
> arithmetic progressions.  You supply the start and finish and it produces
a
> list from start up to finish, incrementing by one:
>
> >>> range(5, 10)
> [5, 6, 7, 8, 9]
>
> It is possible to specify a different increment (even negative; sometimes
> this is called the `step'):
>
> >>> range(0, 10, 3)
> [0, 3, 6, 9]
> >>> range(-10, -100, -30)
> [-10, -40, -70]
>
> Calling range() with one number produces the same list that a for
statement
> iterates over for that number:
>
> >>> range(10)
> [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>
> --- end tutorial ---
>
> I like this proposal and would like to see it adopted.  If others like it,
> they should speak up since about all we hear from are the detractors.
>
> Jeremy Cromwell
>
> ...now let's see..<PrtScnSysRq>...<PgUp>...Hmmm, where's that <wink> key?
>
>