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Several additions and updates based on text from Marc-Andre Lemburg

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<mal@lemburg.com>.

Lots of markup reformatting to make it easier for me to read & maintain.
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Fred Drake 2000-10-25 20:59:52 +00:00
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Doc/lib/liblocale.tex
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@ -3,15 +3,15 @@
\declaremodule{standard}{locale}
\modulesynopsis{Internationalization services.}
\moduleauthor{Martin von Loewis}{loewis@informatik.hu-berlin.de}
\sectionauthor{Martin von Loewis}{loewis@informatik.hu-berlin.de}
\moduleauthor{Martin von L\"owis}{loewis@informatik.hu-berlin.de}
\sectionauthor{Martin von L\"owis}{loewis@informatik.hu-berlin.de}
The \module{locale} module opens access to the \POSIX{} locale database
and functionality. The \POSIX{} locale mechanism allows programmers
to deal with certain cultural issues in an application, without
requiring the programmer to know all the specifics of each country
where the software is executed.
The \module{locale} module opens access to the \POSIX{} locale
database and functionality. The \POSIX{} locale mechanism allows
programmers to deal with certain cultural issues in an application,
without requiring the programmer to know all the specifics of each
country where the software is executed.
The \module{locale} module is implemented on top of the
\module{_locale}\refbimodindex{_locale} module, which in turn uses an
@ -21,170 +21,267 @@ The \module{locale} module defines the following exception and
functions:
\begin{funcdesc}{setlocale}{category\optional{, value}}
If \var{value} is specified, modifies the locale setting for the
\var{category}. The available categories are listed in the data
description below. The value is the name of a locale. An empty string
specifies the user's default settings. If the modification of the
locale fails, the exception \exception{Error} is
raised. If successful, the new locale setting is returned.
\begin{excdesc}{Error}
Exception raised when \function{setlocale()} fails.
\end{excdesc}
If no \var{value} is specified, the current setting for the
\var{category} is returned.
\begin{funcdesc}{setlocale}{category\optional{, locale}}
If \var{locale} is specified, it may be a string, a tuple of the
form \code{(\var{language code}, \var{encoding})}, or \code{None}.
If it is a tuple, it is converted to a string using the locale
aliasing engine. If \var{locale} is given and not \code{None},
\function{setlocale()} modifies the locale setting for the
\var{category}. The available categories are listed in the data
description below. The value is the name of a locale. An empty
string specifies the user's default settings. If the modification of
the locale fails, the exception \exception{Error} is raised. If
successful, the new locale setting is returned.
If \var{locale} is omitted or \code{None}, the current setting for
\var{category} is returned.
\function{setlocale()} is not thread safe on most systems.
Applications typically start with a call of
\function{setlocale()} is not thread safe on most systems. Applications
typically start with a call of
\begin{verbatim}
import locale
locale.setlocale(locale.LC_ALL,"")
\end{verbatim}
This sets the locale for all categories to the user's default setting
(typically specified in the \envvar{LANG} environment variable). If
the locale is not changed thereafter, using multithreading should not
cause problems.
\end{funcdesc}
\begin{excdesc}{Error}
Exception raised when \function{setlocale()} fails.
\end{excdesc}
This sets the locale for all categories to the user's default
setting (typically specified in the \envvar{LANG} environment
variable). If the locale is not changed thereafter, using
multithreading should not cause problems.
\versionchanged[Added support for tuple values of the \var{locale}
parameter]{2.0}
\end{funcdesc}
\begin{funcdesc}{localeconv}{}
Returns the database of of the local conventions as a dictionary. This
dictionary has the following strings as keys:
\begin{itemize}
\item \code{decimal_point} specifies the decimal point used in
floating point number representations for the \constant{LC_NUMERIC}
category.
\item \code{grouping} is a sequence of numbers specifying at which
relative positions the \code{thousands_sep} is expected. If the
sequence is terminated with \constant{CHAR_MAX}, no further
grouping is performed. If the sequence terminates with a \code{0}, the last
group size is repeatedly used.
\item \code{thousands_sep} is the character used between groups.
\item \code{int_curr_symbol} specifies the international currency
symbol from the \constant{LC_MONETARY} category.
\item \code{currency_symbol} is the local currency symbol.
\item \code{mon_decimal_point} is the decimal point used in monetary
values.
\item \code{mon_thousands_sep} is the separator for grouping of
monetary values.
\item \code{mon_grouping} has the same format as the \code{grouping}
key; it is used for monetary values.
\item \code{positive_sign} and \code{negative_sign} gives the sign
used for positive and negative monetary quantities.
\item \code{int_frac_digits} and \code{frac_digits} specify the number
of fractional digits used in the international and local formatting
of monetary values.
\item \code{p_cs_precedes} and \code{n_cs_precedes} specifies whether
the currency symbol precedes the value for positive or negative
values.
\item \code{p_sep_by_space} and \code{n_sep_by_space} specifies
whether there is a space between the positive or negative value and
the currency symbol.
\item \code{p_sign_posn} and \code{n_sign_posn} indicate how the
sign should be placed for positive and negative monetary values.
\end{itemize}
Returns the database of of the local conventions as a dictionary.
This dictionary has the following strings as keys:
The possible values for \code{p_sign_posn} and
\code{n_sign_posn} are given below.
\begin{itemize}
\item
\code{'decimal_point'} specifies the decimal point used in floating
point number representations for the \constant{LC_NUMERIC}
category.
\begin{tableii}{c|l}{code}{Value}{Explanation}
\lineii{0}{Currency and value are surrounded by parentheses.}
\lineii{1}{The sign should precede the value and currency symbol.}
\lineii{2}{The sign should follow the value and currency symbol.}
\lineii{3}{The sign should immediately precede the value.}
\lineii{4}{The sign should immediately follow the value.}
\lineii{LC_MAX}{Nothing is specified in this locale.}
\end{tableii}
\item
\code{'groupin'} is a sequence of numbers specifying at which
relative positions the \code{'thousands_sep'} is expected. If the
sequence is terminated with \constant{CHAR_MAX}, no further
grouping is performed. If the sequence terminates with a \code{0},
the last group size is repeatedly used.
\item
\code{'thousands_sep'} is the character used between groups.
\item
\code{'int_curr_symbol'} specifies the international currency
symbol from the \constant{LC_MONETARY} category.
\item
\code{'currency_symbol'} is the local currency symbol.
\item
\code{'mon_decimal_point'} is the decimal point used in monetary
values.
\item
\code{'mon_thousands_sep'} is the separator for grouping of
monetary values.
\item
\code{'mon_grouping'} has the same format as the \code{'grouping'}
key; it is used for monetary values.
\item
\code{'positive_sign'} and \code{'negative_sign'} gives the sign
used for positive and negative monetary quantities.
\item
\code{'int_frac_digits'} and \code{'frac_digits'} specify the number
of fractional digits used in the international and local
formatting of monetary values.
\item
\code{'p_cs_precedes'} and \code{'n_cs_precedes'} specifies whether
the currency symbol precedes the value for positive or negative
values.
\item
\code{'p_sep_by_space'} and \code{'n_sep_by_space'} specifies
whether there is a space between the positive or negative value
and the currency symbol.
\item
\code{'p_sign_posn'} and \code{'n_sign_posn'} indicate how the
sign should be placed for positive and negative monetary values.
\end{itemize}
The possible values for \code{p_sign_posn} and
\code{n_sign_posn} are given below.
\begin{tableii}{c|l}{code}{Value}{Explanation}
\lineii{0}{Currency and value are surrounded by parentheses.}
\lineii{1}{The sign should precede the value and currency symbol.}
\lineii{2}{The sign should follow the value and currency symbol.}
\lineii{3}{The sign should immediately precede the value.}
\lineii{4}{The sign should immediately follow the value.}
\lineii{LC_MAX}{Nothing is specified in this locale.}
\end{tableii}
\end{funcdesc}
\begin{funcdesc}{strcoll}{string1,string2}
Compares two strings according to the current \constant{LC_COLLATE}
setting. As any other compare function, returns a negative, or a
positive value, or \code{0}, depending on whether \var{string1}
collates before or after \var{string2} or is equal to it.
\begin{funcdesc}{getdefaultlocale}{\optional{envvars}}
Tries to determine the default locale settings and returns
them as a tuple of the form \code{(\var{language code},
\var{encoding})}.
According to \POSIX, a program which has not called
\code{setlocale(LC_ALL, '')} runs using the portable \code{'C'}
locale. Calling \code{setlocale(LC_ALL, '')} lets it use the
default locale as defined by the \envvar{LANG} variable. Since we
do not want to interfere with the current locale setting we thus
emulate the behavior in the way described above.
To maintain compatibility with other platforms, not only the
\envvar{LANG} variable is tested, but a list of variables given as
envvars parameter. The first found to be defined will be
used. \var{envvars} defaults to the search path used in GNU gettext;
it must always contain the variable name \samp{LANG}. The GNU
gettext search path contains \code{'LANGUAGE'}, \code{'LC_ALL'},
code{'LC_CTYPE'}, and \code{'LANG'}, in that order.
Except for the code \code{'C'}, the language code corresponds to
\rfc{1766}. \var{language code} and \var{encoding} may be
\code{None} if their values cannot be determined.
\versionadded{2.0}
\end{funcdesc}
\begin{funcdesc}{getlocale}{\optional{category}}
Returns the current setting for the given locale category as
tuple (language code, encoding). \var{category} may be one of the
\constant{LC_*} values except \constant{LC_ALL}. It defaults to
\constant{LC_CTYPE}.
Except for the code \code{'C'}, the language code corresponds to
\rfc{1766}. \var{language code} and \var{encoding} may be
\code{None} if their values cannot be determined.
\versionadded{2.0}
\end{funcdesc}
\begin{funcdesc}{normalize}{localename}
Returns a normalized locale code for the given locale name. The
returned locale code is formatted for use with
\function{setlocale()}. If normalization fails, the original name
is returned unchanged.
If the given encoding is not known, the function defaults to
the default encoding for the locale code just like
\function{setlocale()}.
\versionadded{2.0}
\end{funcdesc}
\begin{funcdesc}{resetlocale}{\optional{category}}
Sets the locale for \var{category} to the default setting.
The default setting is determined by calling
\function{getdefaultlocale()}. \var{category} defaults to
\constant{LC_ALL}.
\versionadded{2.0}
\end{funcdesc}
\begin{funcdesc}{strcoll}{string1, string2}
Compares two strings according to the current
\constant{LC_COLLATE} setting. As any other compare function,
returns a negative, or a positive value, or \code{0}, depending on
whether \var{string1} collates before or after \var{string2} or is
equal to it.
\end{funcdesc}
\begin{funcdesc}{strxfrm}{string}
Transforms a string to one that can be used for the built-in function
\function{cmp()}\bifuncindex{cmp}, and still returns locale-aware
results. This function can be used when the same string is compared
repeatedly, e.g. when collating a sequence of strings.
Transforms a string to one that can be used for the built-in
function \function{cmp()}\bifuncindex{cmp}, and still returns
locale-aware results. This function can be used when the same
string is compared repeatedly, e.g. when collating a sequence of
strings.
\end{funcdesc}
\begin{funcdesc}{format}{format, val, \optional{grouping\code{ = 0}}}
Formats a number \var{val} according to the current
\constant{LC_NUMERIC} setting. The format follows the conventions of
the \code{\%} operator. For floating point values, the decimal point
is modified if appropriate. If \var{grouping} is true, also takes the
grouping into account.
\begin{funcdesc}{format}{format, val\optional{, grouping}}
Formats a number \var{val} according to the current
\constant{LC_NUMERIC} setting. The format follows the conventions
of the \code{\%} operator. For floating point values, the decimal
point is modified if appropriate. If \var{grouping} is true, also
takes the grouping into account.
\end{funcdesc}
\begin{funcdesc}{str}{float}
Formats a floating point number using the same format as the built-in
function \code{str(\var{float})}, but takes the decimal point into
account.
Formats a floating point number using the same format as the
built-in function \code{str(\var{float})}, but takes the decimal
point into account.
\end{funcdesc}
\begin{funcdesc}{atof}{string}
Converts a string to a floating point number, following the
\constant{LC_NUMERIC} settings.
Converts a string to a floating point number, following the
\constant{LC_NUMERIC} settings.
\end{funcdesc}
\begin{funcdesc}{atoi}{string}
Converts a string to an integer, following the \constant{LC_NUMERIC}
conventions.
Converts a string to an integer, following the
\constant{LC_NUMERIC} conventions.
\end{funcdesc}
\begin{datadesc}{LC_CTYPE}
\refstmodindex{string}
Locale category for the character type functions. Depending on the
settings of this category, the functions of module \refmodule{string}
dealing with case change their behaviour.
Locale category for the character type functions. Depending on the
settings of this category, the functions of module
\refmodule{string} dealing with case change their behaviour.
\end{datadesc}
\begin{datadesc}{LC_COLLATE}
Locale category for sorting strings. The functions
\function{strcoll()} and \function{strxfrm()} of the \module{locale}
module are affected.
Locale category for sorting strings. The functions
\function{strcoll()} and \function{strxfrm()} of the
\module{locale} module are affected.
\end{datadesc}
\begin{datadesc}{LC_TIME}
Locale category for the formatting of time. The function
\function{time.strftime()} follows these conventions.
Locale category for the formatting of time. The function
\function{time.strftime()} follows these conventions.
\end{datadesc}
\begin{datadesc}{LC_MONETARY}
Locale category for formatting of monetary values. The available
options are available from the \function{localeconv()} function.
Locale category for formatting of monetary values. The available
options are available from the \function{localeconv()} function.
\end{datadesc}
\begin{datadesc}{LC_MESSAGES}
Locale category for message display. Python currently does not support
application specific locale-aware messages. Messages displayed by the
operating system, like those returned by \function{os.strerror()}
might be affected by this category.
Locale category for message display. Python currently does not
support application specific locale-aware messages. Messages
displayed by the operating system, like those returned by
\function{os.strerror()} might be affected by this category.
\end{datadesc}
\begin{datadesc}{LC_NUMERIC}
Locale category for formatting numbers. The functions
\function{format()}, \function{atoi()}, \function{atof()} and
\function{str()} of the \module{locale} module are affected by that
category. All other numeric formatting operations are not affected.
Locale category for formatting numbers. The functions
\function{format()}, \function{atoi()}, \function{atof()} and
\function{str()} of the \module{locale} module are affected by that
category. All other numeric formatting operations are not
affected.
\end{datadesc}
\begin{datadesc}{LC_ALL}
Combination of all locale settings. If this flag is used when the
locale is changed, setting the locale for all categories is
attempted. If that fails for any category, no category is changed at
all. When the locale is retrieved using this flag, a string indicating
the setting for all categories is returned. This string can be later
used to restore the settings.
Combination of all locale settings. If this flag is used when the
locale is changed, setting the locale for all categories is
attempted. If that fails for any category, no category is changed at
all. When the locale is retrieved using this flag, a string
indicating the setting for all categories is returned. This string
can be later used to restore the settings.
\end{datadesc}
\begin{datadesc}{CHAR_MAX}
This is a symbolic constant used for different values returned by
\function{localeconv()}.
This is a symbolic constant used for different values returned by
\function{localeconv()}.
\end{datadesc}
Example:
@ -199,6 +296,7 @@ Example:
>>> locale.setlocale(locale.LC_ALL, loc) # restore saved locale
\end{verbatim}
\subsection{Background, details, hints, tips and caveats}
The C standard defines the locale as a program-wide property that may
@ -243,8 +341,8 @@ is to use the special functions defined by this module:
\function{atof()}, \function{atoi()}, \function{format()},
\function{str()}.
\subsection{For extension writers and programs that embed Python}
\label{embedding-locale}
\subsection{For extension writers and programs that embed Python
\label{embedding-locale}}
Extension modules should never call \function{setlocale()}, except to
find out what the current locale is. But since the return value can