supply \programopt{-Walways::PendingDeprecationWarning::} on the
command line or use \function{warnings.filterwarnings()}.
+\item The process of deprecating string-based exceptions, as
+in \code{raise "Error occurred"}, has begun. Raising a string will
+now trigger \exception{PendingDeprecationWarning}.
+
\item Using \code{None} as a variable name will now result in a
\exception{SyntaxWarning} warning. In a future version of Python,
\code{None} may finally become a keyword.
class's ancestors, but 2.3 now uses the C3 algorithm as described in
the paper \ulink{``A Monotonic Superclass Linearization for
Dylan''}{http://www.webcom.com/haahr/dylan/linearization-oopsla96.html}.
-To understand the motivation for this change, read the thread on
-python-dev starting with the message at
+To understand the motivation for this change,
+read Michele Simionato's article
+\ulink{``Python 2.3 Method Resolution Order''}{http://www.phyast.pitt.edu/~micheles/mro.html}, or
+read the thread on python-dev starting with the message at
\url{http://mail.python.org/pipermail/python-dev/2002-October/029035.html}.
Samuele Pedroni first pointed out the problem and also implemented the
fix by coding the C3 algorithm.