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Date: Sat, 20 Apr 2013 19:34:22 -0500
From: Tim Chase <python.list@tim.thechases.com>
To: Steven D'Aprano <steve+comp.lang.python@pearwood.info>
Subject: Re: There must be a better way
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On 2013-04-21 00:06, Steven D'Aprano wrote:
> On Sat, 20 Apr 2013 19:46:07 -0400, Colin J. Williams wrote:
> 
> > Below is part of a script which shows the changes made to permit
> > the script to run on either Python 2.7 or Python 3.2.
> > 
> > I was surprised to see that the CSV next method is no longer
> > available.
> 
> This makes no sense. What's "the CSV next method"? Are you talking
> about the csv module? It has no "next method".

In 2.x, the csv.reader() class (and csv.DictReader() class) offered
a .next() method that is absent in 3.x  For those who use(d) the
csv.reader object on a regular basis, this was a pretty common
usage.  Particularly if you had to do your own header parsing:

  f = open(...)
  r = csv.reader(f)
  try:
    headers = r.next()
    header_map = analyze(headers)
    for row in r:
      foo = row[header_map["FOO COLUMN"]]
      process(foo)
  finally:
    f.close()

(I did this for a number of cases where the client couldn't
consistently send column-headers in a consistent
capitalization/spaces, so my header-making function had to normalize
the case/spaces and then reference the normalized names)

> So provided you are using Python 2.6 or better, you call:
> 
> next(inData)
> 
> to get the next value, regardless of whether it is Python 2.x or
> 3.x.
> 
> If you need to support older versions, you can do this:
> 
> try:
>     next  # Does the built-in already exist?
> except NameError:
>     # No, we define our own.
>     def next(iterator):
>         return iterator.next()
> 
> then just use next(inData) as normal.

This is a good expansion of Chris Rebert's suggestion to use next(),
as those of us that have to support pre-2.6 code lack the next()
function out of the box.

-tkc