\section{PEP 331: Locale-Independent Float/String Conversions}

The \module{locale} modules lets Python software select various

conversions and display conventions that are localized to a particular

country or language. However, the module was careful to not change

the numeric locale because various functions in Python's

implementation required that the numeric locale remain set to the

\code{'C'} locale. Often this was because the code was using the C library's

\cfunction{atof()} function.

Not setting the numeric locale caused trouble for extensions that used

third-party C libraries, however, because they wouldn't have the

correct locale set. The motivating example was GTK+, whose user

interface widgets weren't displaying numbers in the current locale.

The solution described in the PEP is to add three new functions to the

Python API that perform ASCII-only conversions, ignoring the locale

setting:

\begin{itemize}

\item \cfunction{PyOS_ascii_strtod(\var{str}, \var{ptr})}

and \cfunction{PyOS_ascii_atof(\var{str}, \var{ptr})}

both convert a string to a C \ctype{double}.

\item \cfunction{PyOS_ascii_formatd(\var{buffer}, \var{buf_len}, \var{format}, \var{d})} converts a \ctype{double} to an ASCII string.

\end{itemize}

The code for these functions came from the GLib library

(\url{http://developer.gnome.org/arch/gtk/glib.html}), whose

developers kindly relicensed the relevant functions and donated them

to the Python Software Foundation. The \module{locale} module

can now change the numeric locale, letting extensions such as GTK+

produce the correct results.

\begin{seealso}

\seepep{331}{Locale-Independent Float/String Conversions}{Written by Christian R. Reis, and implemented by Gustavo Carneiro.}

\end{seealso}

\item \constant{None} is now a constant; code that binds a new value to

the name \samp{None} is now a syntax error.

were optimized and now run about one-third faster. The inner loops

were also optimized for dictionaries, resulting in performance boosts for

\method{keys()}, \method{values()}, \method{items()},

\method{iterkeys()}, \method{itervalues()}, and \method{iteritems()}.