Describe new functions and variables for locales.

3 files changed, 88 insertions, 20 deletions

diff --git a/etc/NEWS b/etc/NEWS
index dcddc4d025e..6a2b2370f50 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -377,6 +377,10 @@ Shell script mode (sh-script) can now indent scripts for shells
 derived from sh and rc.  The indentation style is customizeable, and
 sh-script can attempt to "learn" the current buffer's style.
 
+** Emacs now attempts to determine the initial language environment
+and preferred and locale coding systems systematically from the
+LC_ALL, LC_CTYPE, and LANG environment variables during startup.
+
 ** New language environments `Latin-8' and `Latin-9'.
 These correspond respectively to the ISO character sets 8859-14
 (Celtic) and 8859-15 (updated Latin-1, with the Euro sign).  There is
@@ -483,6 +487,24 @@ Note that +++ before an item means the Lisp manual has been updated.
 When you add a new item, please add it without either +++ or ---
 so I will know I still need to look at it -- rms.
 
+** New functions and variables for locales.
+
+The new variable `locale-coding-system' specifies how to encode and
+decode strings passed to low-level message functions like strerror and
+time functions like strftime.  The new variables `messages-locale' and
+`time-locale' give the system locales to be used during the next
+invocations of these two types of functions; the new variables
+`previous-messages-locale' and `previous-time-locale' give the locales
+most recently used.
+
+The new function `set-locale-environment' sets the language
+environment, preferred coding system, and locale coding system from
+the system locale as specified by the LC_ALL, LC_CTYPE, and LANG
+environment variables.  It is normally invoked during startup.  It
+uses the new variables `locale-language-names',
+`locale-charset-language-names', and `locale-preferred-coding-systems'
+to make its decisions.
+
 ** syntax tables now understand nested comments.
 To declare a comment syntax as allowing nesting, just add an `n'
 modifier to either of the characters of the comment end and the comment
diff --git a/man/cmdargs.texi b/man/cmdargs.texi
index 97df157ddcb..692ea00a68a 100644
--- a/man/cmdargs.texi
+++ b/man/cmdargs.texi
@@ -338,14 +338,19 @@ to search for files.
 @item INFOPATH
 A colon-separated list of directories holding info files.  Setting this
 variable overrides the setting in @file{paths.el} when Emacs was built.
-@item LANG
-@itemx LC_ALL
+@item LC_ALL
 @itemx LC_CTYPE
-The user's preferred locale.  A locale name which contains
-@samp{8859-@var{n}}, @samp{8859_@var{n}} or @samp{8859@var{n}}, where
-@var{n} is between 1 and 4, automatically specifies the
-@samp{Latin-@var{n}} language environment when Emacs starts up.  If
-@var{n} is 9, that specifies @samp{Latin-5}.
+@itemx LANG
+@findex set-locale-environment
+@vindex locale-language-names
+@vindex locale-charset-language-names
+@vindex locale-preferred-coding-systems
+The user's locale, matched by @code{set-locale-environment} against
+entries in @code{locale-language-names},
+@code{locale-charset-language-names}, and
+@code{locale-preferred-coding-systems} to select a default language
+environment and coding system.  The first of these environment variables
+with a nonempty value specifies the locale.
 @item LOGNAME
 The user's login name.  See also @code{USER}.
 @item MAIL
diff --git a/man/mule.texi b/man/mule.texi
index c6377e7c77e..09962e3d111 100644
--- a/man/mule.texi
+++ b/man/mule.texi
@@ -9,23 +9,24 @@
 @cindex encoding of characters
 
 @cindex Chinese
+@cindex Cyrillic
 @cindex Devanagari
 @cindex Hindi
 @cindex Marathi
-@cindex Ethiopian
+@cindex Ethiopic
 @cindex Greek
+@cindex Hebrew
 @cindex IPA
 @cindex Japanese
 @cindex Korean
 @cindex Lao
-@cindex Russian
 @cindex Thai
 @cindex Tibetan
 @cindex Vietnamese
   Emacs supports a wide variety of international character sets,
 including European variants of the Latin alphabet, as well as Chinese,
-Devanagari (Hindi and Marathi), Ethiopian, Greek, IPA, Japanese, Korean,
-Lao, Russian, Thai, Tibetan, and Vietnamese scripts.  These features
+Cyrillic, Devanagari (Hindi and Marathi), Ethiopic, Greek, Hebrew, IPA,
+Japanese, Korean, Lao, Thai, Tibetan, and Vietnamese scripts.  These features
 have been merged from the modified version of Emacs known as MULE (for
 ``MULti-lingual Enhancement to GNU Emacs'')
 
@@ -147,23 +148,54 @@ also specify the default coding system to use when you create a file.
 Each language environment also specifies a default input method.
 
 @findex set-language-environment
-  The way to select a language environment is with the command @kbd{M-x
+@vindex current-language-environment
+  To select a language environment, customize the option
+@code{current-language-environment} or use the command @kbd{M-x
 set-language-environment}.  It makes no difference which buffer is
 current when you use this command, because the effects apply globally to
 the Emacs session.  The supported language environments include:
 
 @quotation
-Chinese-BIG5, Chinese-CNS, Chinese-GB, Cyrillic-Alternativnyj,
-Cyrillic-ISO, Cyrillic-KOI8, Devanagari, English, Ethiopic, Greek,
-Hebrew, Japanese, Korean, Lao, Latin-1, Latin-2, Latin-3, Latin-4,
-Latin-5, Thai, Tibetan, and Vietnamese.
+Chinese-BIG5, Chinese-CNS, Chinese-GB, Cyrillic-ALT, Cyrillic-ISO,
+Cyrillic-KOI8, Czech, Devanagari, English, Ethiopic, German, Greek,
+Hebrew, IPA, Japanese, Korean, Lao, Latin-1, Latin-2, Latin-3,
+Latin-4, Latin-5, Latin-8, Latin-9, Romanian, Slovak, Slovenian, Thai,
+Tibetan, Turkish, and Vietnamese.
 @end quotation
 
+@findex set-locale-environment
+@vindex locale-language-names
+@vindex locale-charset-language-names
   Some operating systems let you specify the language you are using by
-setting locale environment variables.  Emacs handles one common special
-case of this: if your locale name for character types contains the
-string @samp{8859-@var{n}}, Emacs automatically selects the
-corresponding language environment.
+setting the locale environment variables @env{LC_ALL}, @env{LC_CTYPE},
+and @env{LANG}; the first of these which is nonempty specifies your
+locale.  Emacs handles this during startup by invoking the
+@code{set-locale-environment} function, which matches your locale
+against entries in the value of the variable
+@code{locale-language-names} and selects the corresponding language
+environment if a match is found.  But if your locale also matches an
+entry in the variable @code{locale-charset-language-names}, this entry
+is preferred if its character set disagrees.  For example, suppose the
+locale @samp{en_GB.ISO8859-15} matches @code{"Latin-1"} in
+@code{locale-language-names} and @code{"Latin-9"} in
+@code{locale-charset-language-names}; since these two language
+environments' character sets disagree, Emacs uses @code{"Latin-9"}.
+
+@findex set-locale-environment
+@vindex locale-preferred-coding-systems
+  The @code{set-locale-environment} function normally uses the preferred
+coding system established by the language environment to decode system
+messages.  But if your locale matches an entry in the variable
+@code{locale-preferred-coding-systems}, Emacs uses the corresponding
+coding system instead.  For example, if the locale @samp{ja_JP.PCK}
+matches @code{japanese-shift-jis} in
+@code{locale-preferred-coding-systems}, Emacs uses that encoding even
+though it might normally use @code{japanese-iso-8bit}.
+
+  The environment chosen from the locale when Emacs starts is
+overidden by any explicit use of the command
+@code{set-language-environment} or customization of
+@code{current-language-environment} in your init file.
 
 @kindex C-h L
 @findex describe-language-environment
@@ -750,6 +782,15 @@ these buffers under the visited file name, saving may use the wrong file
 name, or it may get an error.  If such a problem happens, use @kbd{C-x
 C-w} to specify a new file name for that buffer.
 
+@vindex locale-coding-system
+  The variable @code{locale-coding-system} specifies a coding system to
+use when encoding and decoding system strings such as system error
+messages and @code{format-time-string} formats and time stamps.  This
+coding system should be compatible with the underlying system's coding
+system, which is normally specified by the first environment variable in
+the list @env{LC_ALL}, @env{LC_CTYPE}, @env{LANG} whose value is
+nonempty.
+
 @node Fontsets
 @section Fontsets
 @cindex fontsets