PEP 3114: rename .next() to .__next__() and add next() builtin.

Doc/api/newtypes.tex

@@ -1071,7 +1071,7 @@ The next two fields only exist if the
   iterator, or raises \exception{StopIteration} when the iterator is
   exhausted.  Its presence normally signals that the instances of this
   type are iterators (although classic instances always have this
-  function, even if they don't define a \method{next()} method).
+  function, even if they don't define a \method{__next__()} method).
 
   Iterator types should also define the \member{tp_iter} function, and
   that function should return the iterator instance itself (not a new

Doc/howto/functional.rst

@@ -199,11 +199,13 @@ foundation for writing functional-style programs: iterators.
 
 An iterator is an object representing a stream of data; this object
 returns the data one element at a time.  A Python iterator must
-support a method called ``next()`` that takes no arguments and always
+support a method called ``__next__()`` that takes no arguments and always
 returns the next element of the stream.  If there are no more elements
-in the stream, ``next()`` must raise the ``StopIteration`` exception.
+in the stream, ``__next__()`` must raise the ``StopIteration`` exception.
 Iterators don't have to be finite, though; it's perfectly reasonable
 to write an iterator that produces an infinite stream of data.
+The built-in ``next()`` function is normally used to call the iterator's
+``__next__()`` method.
 
 The built-in ``iter()`` function takes an arbitrary object and tries
 to return an iterator that will return the object's contents or
@@ -218,13 +220,13 @@ You can experiment with the iteration interface manually::
     >>> it = iter(L)
     >>> print it
     <iterator object at 0x8116870>
-    >>> it.next()
+    >>> next(it)
     1
-    >>> it.next()
+    >>> next(it)
     2
-    >>> it.next()
+    >>> next(it)
     3
-    >>> it.next()
+    >>> next(it)
     Traceback (most recent call last):
       File "<stdin>", line 1, in ?
     StopIteration
@@ -271,7 +273,7 @@ won't return either.
 Note that you can only go forward in an iterator; there's no way to
 get the previous element, reset the iterator, or make a copy of it.
 Iterator objects can optionally provide these additional capabilities,
-but the iterator protocol only specifies the ``next()`` method.
+but the iterator protocol only specifies the ``__next__()`` method.
 Functions may therefore consume all of the iterator's output, and if
 you need to do something different with the same stream, you'll have
 to create a new iterator.
@@ -485,7 +487,7 @@ outputs the value of ``i``, similar to a ``return``
 statement.  The big difference between ``yield`` and a
 ``return`` statement is that on reaching a ``yield`` the
 generator's state of execution is suspended and local variables are
-preserved.  On the next call to the generator's ``.next()`` method,
+preserved.  On the next call ``next(generator)``,
 the function will resume executing.  
 
 Here's a sample usage of the ``generate_ints()`` generator::
@@ -493,13 +495,13 @@ Here's a sample usage of the ``generate_ints()`` generator::
     >>> gen = generate_ints(3)
     >>> gen
     <generator object at 0x8117f90>
-    >>> gen.next()
+    >>> next(gen)
     0
-    >>> gen.next()
+    >>> next(gen)
     1
-    >>> gen.next()
+    >>> next(gen)
     2
-    >>> gen.next()
+    >>> next(gen)
     Traceback (most recent call last):
       File "stdin", line 1, in ?
       File "stdin", line 2, in generate_ints
@@ -521,7 +523,7 @@ You could achieve the effect of generators manually by writing your
 own class and storing all the local variables of the generator as
 instance variables.  For example, returning a list of integers could
 be done by setting ``self.count`` to 0, and having the
-``next()`` method increment ``self.count`` and return it.
+``__next__()`` method increment ``self.count`` and return it.
 However, for a moderately complicated generator, writing a
 corresponding class can be much messier.
 
@@ -583,7 +585,7 @@ use parentheses when there's an operation, as in ``val = (yield i)
 Values are sent into a generator by calling its
 ``send(value)`` method.  This method resumes the 
 generator's code and the ``yield`` expression returns the specified
-value.  If the regular ``next()`` method is called, the
+value.  If the regular ``__next__()`` method is called, the
 ``yield`` returns ``None``.
 
 Here's a simple counter that increments by 1 and allows changing the
@@ -604,18 +606,18 @@ value of the internal counter.
 And here's an example of changing the counter:
 
     >>> it = counter(10)
-    >>> print it.next()
+    >>> print next(it)
     0
-    >>> print it.next()
+    >>> print next(it)
     1
     >>> print it.send(8)
     8
-    >>> print it.next()
+    >>> print next(it)
     9
-    >>> print it.next()
+    >>> print next(it)
     Traceback (most recent call last):
       File ``t.py'', line 15, in ?
-        print it.next()
+        print next(it)
     StopIteration
 
 Because ``yield`` will often be returning ``None``, you

Doc/lib/libcollections.tex

@@ -174,7 +174,7 @@ def roundrobin(*iterables):
     while pending:
         task = pending.popleft()
         try:
-            yield task.next()
+            yield next(task)
         except StopIteration:
             continue
         pending.append(task)
@@ -315,12 +315,12 @@ letter.
 
 The function \function{int()} which always returns zero is just a special
 case of constant functions.  A faster and more flexible way to create
-constant functions is to use \function{itertools.repeat()} which can supply
+constant functions is to use a lambda function which can supply
 any constant value (not just zero):
 
 \begin{verbatim}
 >>> def constant_factory(value):
-...     return itertools.repeat(value).next
+...     return lambda: value
 >>> d = defaultdict(constant_factory('<missing>'))
 >>> d.update(name='John', action='ran')
 >>> '%(name)s %(action)s to %(object)s' % d

Doc/lib/libcsv.tex

@@ -487,8 +487,8 @@ class UTF8Recoder:
     def __iter__(self):
         return self
 
-    def next(self):
-        return self.reader.next().encode("utf-8")
+    def __next__(self):
+        return next(self.reader).encode("utf-8")
 
 class UnicodeReader:
     """
@@ -500,8 +500,8 @@ class UnicodeReader:
         f = UTF8Recoder(f, encoding)
         self.reader = csv.reader(f, dialect=dialect, **kwds)
 
-    def next(self):
-        row = self.reader.next()
+    def __next__(self):
+        row = next(self.reader)
         return [unicode(s, "utf-8") for s in row]
 
     def __iter__(self):

Doc/lib/libdis.tex

@@ -529,10 +529,10 @@ Set byte code counter to \var{target}.
 \end{opcodedesc}
 
 \begin{opcodedesc}{FOR_ITER}{delta}
-\code{TOS} is an iterator.  Call its \method{next()} method.  If this
-yields a new value, push it on the stack (leaving the iterator below
-it).  If the iterator indicates it is exhausted  \code{TOS} is
-popped, and the byte code counter is incremented by \var{delta}.
+  \code{TOS} is an iterator.  Call its \method{__next__()} method.  If this
+  yields a new value, push it on the stack (leaving the iterator below it).  If
+  the iterator indicates it is exhausted \code{TOS} is popped, and the byte code
+  counter is incremented by \var{delta}.
 \end{opcodedesc}
 
 %\begin{opcodedesc}{FOR_LOOP}{delta}

Doc/lib/libexcs.tex

@@ -265,8 +265,8 @@ Raised when an \keyword{assert} statement fails.
 \end{excdesc}
 
 \begin{excdesc}{StopIteration}
-  Raised by an iterator's \method{next()} method to signal that there
-  are no further values.
+  Raised by builtin \function{next()} and an iterator's \method{__next__()}
+  method to signal that there are no further values.
   This is derived from \exception{Exception} rather than
   \exception{StandardError}, since this is not considered an error in
   its normal application.

Doc/lib/libfuncs.tex

@@ -342,14 +342,12 @@ class C:
 \end{funcdesc}
 
 \begin{funcdesc}{enumerate}{iterable}
-  Return an enumerate object. \var{iterable} must be a sequence, an
-  iterator, or some other object which supports iteration.  The
-  \method{next()} method of the iterator returned by
-  \function{enumerate()} returns a tuple containing a count (from
-  zero) and the corresponding value obtained from iterating over
-  \var{iterable}.  \function{enumerate()} is useful for obtaining an
-  indexed series: \code{(0, seq[0])}, \code{(1, seq[1])}, \code{(2,
-  seq[2])}, \ldots.
+  Return an enumerate object. \var{iterable} must be a sequence, an iterator, or
+  some other object which supports iteration.  The \method{__next__()} method of
+  the iterator returned by \function{enumerate()} returns a tuple containing a
+  count (from zero) and the corresponding value obtained from iterating over
+  \var{iterable}.  \function{enumerate()} is useful for obtaining an indexed
+  series: \code{(0, seq[0])}, \code{(1, seq[1])}, \code{(2, seq[2])}, \ldots.
   \versionadded{2.3}
 \end{funcdesc}
 
@@ -615,7 +613,7 @@ class C:
   support either of those protocols, \exception{TypeError} is raised.
   If the second argument, \var{sentinel}, is given, then \var{o} must
   be a callable object.  The iterator created in this case will call
-  \var{o} with no arguments for each call to its \method{next()}
+  \var{o} with no arguments for each call to its \method{__next__()}
   method; if the value returned is equal to \var{sentinel},
   \exception{StopIteration} will be raised, otherwise the value will
   be returned.
@@ -695,6 +693,12 @@ class C:
   \versionchanged[Added support for the optional \var{key} argument]{2.5}
 \end{funcdesc}
 
+\begin{funcdesc}{next}{iterator\optional{, default}}
+  Retrieve the next item from the \var{iterable} by calling its
+  \method{__next__()} method.  If \var{default} is given, it is returned if the
+  iterator is exhausted, otherwise \exception{StopIteration} is raised.
+\end{funcdesc}
+
 \begin{funcdesc}{object}{}
   Return a new featureless object.  \class{object} is a base
   for all new style classes.  It has the methods that are common

Doc/lib/libitertools.tex

@@ -164,16 +164,16 @@ by functions or loops that truncate the stream.
             self.tgtkey = self.currkey = self.currvalue = xrange(0)
         def __iter__(self):
             return self
-        def next(self):
+        def __next__(self):
             while self.currkey == self.tgtkey:
-                self.currvalue = self.it.next() # Exit on StopIteration
+                self.currvalue = next(self.it) # Exit on StopIteration
                 self.currkey = self.keyfunc(self.currvalue)
             self.tgtkey = self.currkey
             return (self.currkey, self._grouper(self.tgtkey))
         def _grouper(self, tgtkey):
             while self.currkey == tgtkey:
                 yield self.currvalue
-                self.currvalue = self.it.next() # Exit on StopIteration
+                self.currvalue = next(self.it) # Exit on StopIteration
                 self.currkey = self.keyfunc(self.currvalue)
   \end{verbatim}
   \versionadded{2.4}
@@ -227,7 +227,7 @@ by functions or loops that truncate the stream.
      def imap(function, *iterables):
          iterables = map(iter, iterables)
          while True:
-             args = [i.next() for i in iterables]
+             args = [next(i) for i in iterables]
              if function is None:
                  yield tuple(args)
              else:
@@ -253,11 +253,11 @@ by functions or loops that truncate the stream.
      def islice(iterable, *args):
          s = slice(*args)
          it = iter(xrange(s.start or 0, s.stop or sys.maxint, s.step or 1))
-         nexti = it.next()
+         nexti = next(it)
          for i, element in enumerate(iterable):
              if i == nexti:
                  yield element
-                 nexti = it.next()          
+                 nexti = next(it)
   \end{verbatim}
 
   If \var{start} is \code{None}, then iteration starts at zero.
@@ -276,7 +276,7 @@ by functions or loops that truncate the stream.
      def izip(*iterables):
          iterables = map(iter, iterables)
          while iterables:
-             result = [it.next() for it in iterables]
+             result = [next(it) for it in iterables]
              yield tuple(result)
   \end{verbatim}
 
@@ -297,7 +297,7 @@ by functions or loops that truncate the stream.
   from each iterator in-turn, but the process ends when one of the iterators
   terminates.  This leaves the last fetched values in limbo (they cannot be
   returned in a final, incomplete tuple and they are cannot be pushed back
-  into the iterator for retrieval with \code{it.next()}).  In general,
+  into the iterator for retrieval with \code{next(it)}).  In general,
   \function{izip()} should only be used with unequal length inputs when you
   don't care about trailing, unmatched values from the longer iterables.
 \end{funcdesc}
@@ -360,7 +360,7 @@ by functions or loops that truncate the stream.
      def starmap(function, iterable):
          iterable = iter(iterable)
          while True:
-             yield function(*iterable.next())
+             yield function(*next(iterable))
   \end{verbatim}
 \end{funcdesc}
 
@@ -393,7 +393,7 @@ by functions or loops that truncate the stream.
                      item = data.pop(i)
                  yield item
          it = iter(iterable)
-         return (gen(it.next), gen(it.next))
+         return (gen(it.__next__), gen(it.__next__))
   \end{verbatim}
 
   Note, once \function{tee()} has made a split, the original \var{iterable}
@@ -556,10 +556,7 @@ def repeatfunc(func, times=None, *args):
 def pairwise(iterable):
     "s -> (s0,s1), (s1,s2), (s2, s3), ..."
     a, b = tee(iterable)
-    try:
-        b.next()
-    except StopIteration:
-        pass
+    next(b, None)
     return izip(a, b)
 
 def grouper(n, iterable, padvalue=None):

Doc/lib/libstdtypes.tex

@@ -388,18 +388,17 @@ general and specific sequence types, dictionaries, and other more
 specialized forms.  The specific types are not important beyond their
 implementation of the iterator protocol.
 
-The intention of the protocol is that once an iterator's
-\method{next()} method raises \exception{StopIteration}, it will
-continue to do so on subsequent calls.  Implementations that
-do not obey this property are deemed broken.  (This constraint
-was added in Python 2.3; in Python 2.2, various iterators are
-broken according to this rule.)
+The intention of the protocol is that once an iterator's \method{__next__()}
+method raises \exception{StopIteration}, it will continue to do so on subsequent
+calls.  Implementations that do not obey this property are deemed broken.  (This
+constraint was added in Python 2.3; in Python 2.2, various iterators are broken
+according to this rule.)
 
-Python's generators provide a convenient way to implement the
-iterator protocol.  If a container object's \method{__iter__()}
-method is implemented as a generator, it will automatically
-return an iterator object (technically, a generator object)
-supplying the \method{__iter__()} and \method{next()} methods.
+Python's generators provide a convenient way to implement the iterator protocol.
+If a container object's \method{__iter__()} method is implemented as a
+generator, it will automatically return an iterator object (technically, a
+generator object) supplying the \method{__iter__()} and \method{__next__()}
+methods.
 
 
 \section{Sequence Types ---
@@ -1587,17 +1586,17 @@ finally:
   with a real file, this method should \emph{not} be implemented.}
 \end{methoddesc}
 
-\begin{methoddesc}[file]{next}{}
+\begin{methoddesc}[file]{__next__}{}
 A file object is its own iterator, for example \code{iter(\var{f})} returns
 \var{f} (unless \var{f} is closed).  When a file is used as an
 iterator, typically in a \keyword{for} loop (for example,
-\code{for line in f: print line}), the \method{next()} method is
+\code{for line in f: print line}), the \method{__next__()} method is
 called repeatedly.  This method returns the next input line, or raises
 \exception{StopIteration} when \EOF{} is hit.  In order to make a
 \keyword{for} loop the most efficient way of looping over the lines of
-a file (a very common operation), the \method{next()} method uses a
+a file (a very common operation), the \method{__next__()} method uses a
 hidden read-ahead buffer.  As a consequence of using a read-ahead
-buffer, combining \method{next()} with other file methods (like
+buffer, combining \method{__next__()} with other file methods (like
 \method{readline()}) does not work right.  However, using
 \method{seek()} to reposition the file to an absolute position will
 flush the read-ahead buffer.

Doc/lib/sqlite3/executemany_1.py

@@ -7,7 +7,7 @@ class IterChars:
     def __iter__(self):
         return self
 
-    def next(self):
+    def __next__(self):
         if self.count > ord('z'):
             raise StopIteration
         self.count += 1

Doc/ref/ref3.tex

@@ -633,7 +633,7 @@ A function or method which uses the \keyword{yield} statement (see
 section~\ref{yield}, ``The \keyword{yield} statement'') is called a
 \dfn{generator function}.  Such a function, when called, always
 returns an iterator object which can be used to execute the body of
-the function:  calling the iterator's \method{next()} method will
+the function:  calling the iterator's \method{__next__()} method will
 cause the function to execute until it provides a value using the
 \keyword{yield} statement.  When the function executes a
 \keyword{return} statement or falls off the end, a

Doc/ref/ref5.tex

@@ -222,7 +222,7 @@ evaluating the expression to yield a value that is reached the
 innermost block for each iteration.
 
 Variables used in the generator expression are evaluated lazily
-when the \method{next()} method is called for generator object
+when the \method{__next__()} method is called for generator object
 (in the same fashion as normal generators). However, the leftmost
 \keyword{for} clause is immediately evaluated so that error produced
 by it can be seen before any other possible error in the code that

Doc/ref/ref6.tex

@@ -418,19 +418,18 @@ Using a \keyword{yield} statement in a function definition is
 sufficient to cause that definition to create a generator function
 instead of a normal function.
 
-When a generator function is called, it returns an iterator known as a
-generator iterator, or more commonly, a generator.  The body of the
-generator function is executed by calling the generator's
-\method{next()} method repeatedly until it raises an exception.
+When a generator function is called, it returns an iterator known as a generator
+iterator, or more commonly, a generator.  The body of the generator function is
+executed by calling the generator's \method{__next__()} method repeatedly until
+it raises an exception.
 
-When a \keyword{yield} statement is executed, the state of the
-generator is frozen and the value of \grammartoken{expression_list} is
-returned to \method{next()}'s caller.  By ``frozen'' we mean that all
-local state is retained, including the current bindings of local
-variables, the instruction pointer, and the internal evaluation stack:
-enough information is saved so that the next time \method{next()} is
-invoked, the function can proceed exactly as if the \keyword{yield}
-statement were just another external call.
+When a \keyword{yield} statement is executed, the state of the generator is
+frozen and the value of \grammartoken{expression_list} is returned to
+\method{__next__()}'s caller.  By ``frozen'' we mean that all local state is
+retained, including the current bindings of local variables, the instruction
+pointer, and the internal evaluation stack: enough information is saved so that
+the next time \method{__next__()} is invoked, the function can proceed exactly
+as if the \keyword{yield} statement were just another external call.
 
 As of Python version 2.5, the \keyword{yield} statement is now
 allowed in the \keyword{try} clause of a \keyword{try} ...\ 

Doc/tut/glossary.tex

@@ -117,7 +117,7 @@ contain one or more {}\keyword{for} or \keyword{while} loops that
 \keyword{yield} elements back to the caller.  The function execution is
 stopped at the {}\keyword{yield} keyword (returning the result) and is
 resumed there when the next element is requested by calling the
-\method{next()} method of the returned iterator.
+\method{__next__()} method of the returned iterator.
 
 \index{generator expression}
 \item[generator expression]
@@ -207,10 +207,10 @@ hold the iterator for the duration of the loop.  See also
 \index{iterator}
 \item[iterator]
 An object representing a stream of data.  Repeated calls to the
-iterator's \method{next()} method return successive items in the
+iterator's \method{__next__()} method return successive items in the
 stream.  When no more data is available a \exception{StopIteration}
 exception is raised instead.  At this point, the iterator object is
-exhausted and any further calls to its \method{next()} method just
+exhausted and any further calls to its \method{__next__()} method just
 raise \exception{StopIteration} again.  Iterators are required to have
 an \method{__iter__()} method that returns the iterator object
 itself so every iterator is also iterable and may be used in most

Doc/tut/tut.tex

@@ -4488,34 +4488,35 @@ This style of access is clear, concise, and convenient.  The use of iterators
 pervades and unifies Python.  Behind the scenes, the \keyword{for}
 statement calls \function{iter()} on the container object.  The
 function returns an iterator object that defines the method
-\method{next()} which accesses elements in the container one at a
-time.  When there are no more elements, \method{next()} raises a
+\method{__next__()} which accesses elements in the container one at a
+time.  When there are no more elements, \method{__next__()} raises a
 \exception{StopIteration} exception which tells the \keyword{for} loop
-to terminate.  This example shows how it all works:
+to terminate.  You can call the \method{__next__()} method using the
+\function{next()} builtin; this example shows how it all works:
 
 \begin{verbatim}
 >>> s = 'abc'
 >>> it = iter(s)
 >>> it
 <iterator object at 0x00A1DB50>
->>> it.next()
+>>> next(it)
 'a'
->>> it.next()
+>>> next(it)
 'b'
->>> it.next()
+>>> next(it)
 'c'
->>> it.next()
+>>> next(it)
 
 Traceback (most recent call last):
   File "<stdin>", line 1, in ?
-    it.next()
+    next(it)
 StopIteration
 \end{verbatim}
 
 Having seen the mechanics behind the iterator protocol, it is easy to add
 iterator behavior to your classes.  Define a \method{__iter__()} method
-which returns an object with a \method{next()} method.  If the class defines
-\method{next()}, then \method{__iter__()} can just return \code{self}:
+which returns an object with a \method{__next__()} method.  If the class defines
+\method{__next__()}, then \method{__iter__()} can just return \code{self}:
 
 \begin{verbatim}
 class Reverse:
@@ -4525,7 +4526,7 @@ class Reverse:
         self.index = len(data)
     def __iter__(self):
         return self
-    def next(self):
+    def __next__(self):
         if self.index == 0:
             raise StopIteration
         self.index = self.index - 1
@@ -4545,7 +4546,7 @@ s
 
 Generators are a simple and powerful tool for creating iterators.  They are
 written like regular functions but use the \keyword{yield} statement whenever
-they want to return data.  Each time \method{next()} is called, the
+they want to return data.  Each time \function{next()} is called on it, the
 generator resumes where it left-off (it remembers all the data values and
 which statement was last executed).  An example shows that generators can
 be trivially easy to create:
@@ -4566,7 +4567,7 @@ g
 
 Anything that can be done with generators can also be done with class based
 iterators as described in the previous section.  What makes generators so
-compact is that the \method{__iter__()} and \method{next()} methods are
+compact is that the \method{__iter__()} and \method{__next__()} methods are
 created automatically.
 
 Another key feature is that the local variables and execution state

Lib/StringIO.py

@@ -64,10 +64,10 @@ class StringIO:
     def __iter__(self):
         return self
 
-    def next(self):
+    def __next__(self):
         """A file object is its own iterator, for example iter(f) returns f
         (unless f is closed). When a file is used as an iterator, typically
-        in a for loop (for example, for line in f: print line), the next()
+        in a for loop (for example, for line in f: print line), the __next__()
         method is called repeatedly. This method returns the next input line,
         or raises StopIteration when EOF is hit.
         """

Lib/UserDict.py

@@ -139,7 +139,7 @@ class DictMixin:
         return value
     def popitem(self):
         try:
-            k, v = self.iteritems().next()
+            k, v = next(self.iteritems())
         except StopIteration:
             raise KeyError, 'container is empty'
         del self[k]

Lib/codecs.py

@@ -600,7 +600,7 @@ class StreamReader(Codec):
         self.reset()
         self.stream.seek(offset, whence)
 
-    def next(self):
+    def __next__(self):
 
         """ Return the next decoded line from the input stream."""
         line = self.readline()
@@ -669,10 +669,10 @@ class StreamReaderWriter:
 
         return self.reader.readlines(sizehint)
 
-    def next(self):
+    def __next__(self):
 
         """ Return the next decoded line from the input stream."""
-        return self.reader.next()
+        return next(self.reader)
 
     def __iter__(self):
         return self
@@ -782,10 +782,10 @@ class StreamRecoder:
         data, bytesencoded = self.encode(data, self.errors)
         return data.splitlines(1)
 
-    def next(self):
+    def __next__(self):
 
         """ Return the next decoded line from the input stream."""
-        data = self.reader.next()
+        data = next(self.reader)
         data, bytesencoded = self.encode(data, self.errors)
         return data
 

Lib/contextlib.py

@@ -12,14 +12,14 @@ class GeneratorContextManager(object):
 
     def __enter__(self):
         try:
-            return self.gen.next()
+            return next(self.gen)
         except StopIteration:
             raise RuntimeError("generator didn't yield")
 
     def __exit__(self, type, value, traceback):
         if type is None:
             try:
-                self.gen.next()
+                next(self.gen)
             except StopIteration:
                 return
             else:

Lib/csv.py

@@ -79,17 +79,17 @@ class DictReader:
     def __iter__(self):
         return self
 
-    def next(self):
-        row = self.reader.next()
+    def __next__(self):
+        row = next(self.reader)
         if self.fieldnames is None:
             self.fieldnames = row
-            row = self.reader.next()
+            row = next(self.reader)
 
         # unlike the basic reader, we prefer not to return blanks,
         # because we will typically wind up with a dict full of None
         # values
         while row == []:
-            row = self.reader.next()
+            row = next(self.reader)
         d = dict(zip(self.fieldnames, row))
         lf = len(self.fieldnames)
         lr = len(row)
@@ -351,7 +351,7 @@ class Sniffer:
 
         rdr = reader(StringIO(sample), self.sniff(sample))
 
-        header = rdr.next() # assume first row is header
+        header = next(rdr) # assume first row is header
 
         columns = len(header)
         columnTypes = {}