NAME
msgcat - Tcl message catalog
SYNOPSIS
ppaacckkaaggee rreeqquuiirree TTccll 88..22 ppaacckkaaggee rreeqquuiirree mmssggccaatt 11..33::::mmssggccaatt::::mmcc src-string ?arg arg ...?
::::mmssggccaatt::::mmccmmaaxx ??src-string src-string ...?
::::mmssggccaatt::::mmccllooccaallee ?newLocale? ::::mmssggccaatt::::mmccpprreeffeerreenncceess ::::mmssggccaatt::::mmccllooaadd dirname::::mmssggccaatt::::mmccsseett locale src-string ?translate-string?
::::mmssggccaatt::::mmccmmsseett locale src-trans-list
::::mmssggccaatt::::mmccuunnkknnoowwnn locale src-string
DESCRIPTION
The mmssggccaatt package provides a set of functions that can be used to man-
age multi-lingual user interfaces. Text strings are defined in a
``message catalog'' which is independent from the application, and which can be edited or localized without modifying the application source code. New languages or locales are provided by adding a new file to the message catalog. Use of the message catalog is optional by any application or package, but is encouraged if the application or package wishes to be enabledfor multi-lingual applications.
CCOOMMMMAANNDDSS::::mmssggccaatt::::mmcc src-string ?arg arg ...?
Returns a translation of src-string according to the user's cur-
rent locale. If additional arguments past src-string are given,
the ffoorrmmaatt command is used to substitute the additional argu-
ments in the translation of src-string.
::::mmssggccaatt::::mmcc will search the messages defined in the currentnamespace for a translation of src-string; if none is found, it
will search in the parent of the current namespace, and so on until it reaches the global namespace. If no translation string exists, ::::mmssggccaatt::::mmccuunnkknnoowwnn is called and the string returned from ::::mmssggccaatt::::mmccuunnkknnoowwnn is returned. ::::mmssggccaatt::::mmcc is the main function used to localize an application. Instead of using an English string directly, an application can pass the English string through ::::mmssggccaatt::::mmcc and use the result. If an application is written for a single language in this fashion, then itis easy to add support for additional languages later simply by defin-
ing new message catalog entries.::::mmssggccaatt::::mmccmmaaxx ??src-string src-string ...?
Given several source strings, ::::mmssggccaatt::::mmccmmaaxx returns the length of the longest translated string. This is useful when designing localized GUIs, which may require that all buttons, for example, be a fixed width (which will be the width of the widest button). ::::mmssggccaatt::::mmccllooccaallee ?newLocale? This function sets the locale to newLocale. If newLocale is omitted, the current locale is returned, otherwise the currentlocale is set to newLocale. msgcat stores and compares the
locale in a case-insensitive manner, and returns locales in low-
ercase. The initial locale is determined by the locale speci-
fied in the user's environment. See LLOOCCAALLEE SSPPEECCIIFFIICCAATTIIOONN below for a description of the locale string format. ::::mmssggccaatt::::mmccpprreeffeerreenncceess Returns an ordered list of the locales preferred by the user, based on the user's language specification. The list is ordered from most specific to least preference. The list is derivedfrom the current locale set in msgcat by mmssggccaatt::::mmccllooccaallee, and
cannot be set independently. For example, if the current locale is enUSfunky, then mmssggccaatt::::mmccpprreeffeerreenncceess returns {enUSfunky enUS en}. ::::mmssggccaatt::::mmccllooaadd dirnameSearches the specified directory for files that match the lan-
guage specifications returned by ::::mmssggccaatt::::mmccpprreeffeerreenncceess (note that these are all lowercase), extended by the file extension``.msg''. Each matching file is read in order, assuming a UTF-8
encoding. The file contents are then evaluated as a Tcl script. This means that Unicode characters may be present in the messagefile either directly in their UTF-8 encoded form, or by use of
the backslash-u quoting recognized by Tcl evaluation. The num-
ber of message files which matched the specification and were loaded is returned.::::mmssggccaatt::::mmccsseett locale src-string ?translate-string?
Sets the translation for src-string to translate-string in the
specified locale and the current namespace. If translate-string
is not specified, src-string is used for both. The function
returns translate-string.
::::mmssggccaatt::::mmccmmsseett locale src-trans-list
Sets the translation for multiple source strings in src-trans-
list in the specified locale and the current namespace. src-
trans-list must have an even number of elements and is in the
form {src-string translate-string ?src-string translate-string
...?} mmssggccaatt::::mmccmmsseett can be significantly faster than multiple invocations of mmssggccaatt::::mmccsseett. The function returns the number of translations set.::::mmssggccaatt::::mmccuunnkknnoowwnn locale src-string
This routine is called by ::::mmssggccaatt::::mmcc in the case when a trans-
lation for src-string is not defined in the current locale. The
default action is to return src-string. This procedure can be
redefined by the application, for example to log error messages for each unknown string. The ::::mmssggccaatt::::mmccuunnkknnoowwnn procedure is invoked at the same stack context as the call to ::::mmssggccaatt::::mmcc. The return value of ::::mmssggccaatt::::mmccuunnkknnoowwnn is used as the return value for the call to ::::mmssggccaatt::::mmcc. LLOOCCAALLEE SSPPEECCIIFFIICCAATTIIOONNThe locale is specified to mmssggccaatt by a locale string passed to ::::mmssgg-
ccaatt::::mmccllooccaallee. The locale string consists of a language code, anoptional country code, and an optional system-specific code, each sepa-
rated by ``''. The country and language codes are specified in stan-
dards ISO-639 and ISO-3166. For example, the locale ``en'' specifies
English and ``enUS'' specifies U.S. English.When the msgcat package is first loaded, the locale is initialized
according to the user's environment. The variables eennvv((LLCCAALLLL)), eennvv((LLCCMMEESSSSAAGGEESS)), and eennvv((LLAANNGG)) are examined in order. The first ofthem to have a non-empty value is used to determine the initial locale.
The value is parsed according to the XPG4 pattern language[country][.codeset][@modifier]to extract its parts. The initial locale is then set by calling mmssgg-
ccaatt::::mmccllooccaallee with the argument language[country][modifier]On Windows, if none of those environment variables is set, msgcat will
attempt to extract locale information from the registry. If all these attempts to discover an initial locale from the user's environmentfail, msgcat defaults to an initial locale of ``C''.
When a locale is specified by the user, a ``best match'' search is per-
formed during string translation. For example, if a user specifies enGBFunky, the locales ``enGBFunky'', ``enGB'', and ``en'' are searched in order until a matching translation string is found. If no translation string is available, then ::::mmssggccaatt::::uunnkknnoowwnn is called.NAMESPACES AND MESSAGE CATALOGS
Strings stored in the message catalog are stored relative to the names-
pace from which they were added. This allows multiple packages to use the same strings without fear of collisions with other packages. Italso allows the source string to be shorter and less prone to typo-
graphical error. For example, executing the code mcset en hello "hello from ::" namespace eval foo {mcset en hello "hello from ::foo"} puts [mc hello] namespace eval foo {puts [mc hello]} will print hello from :: hello from ::foo When searching for a translation of a message, the message catalog will search first the current namespace, then the parent of the current namespace, and so on until the global namespace is reached. Thisallows child namespaces to "inherit" messages from their parent names-
pace. For example, executing (in the ``en'' locale) the code mcset en m1 ":: message1" mcset en m2 ":: message2" mcset en m3 ":: message3" namespace eval ::foo { mcset en m2 "::foo message2" mcset en m3 "::foo message3" } namespace eval ::foo::bar { mcset en m3 "::foo::bar message3" } puts "[mc m1]; [mc m2]; [mc m3]" namespace eval ::foo {puts "[mc m1]; [mc m2]; [mc m3]"} namespace eval ::foo::bar {puts "[mc m1]; [mc m2]; [mc m3]"} will print :: message1; :: message2; :: message3 :: message1; ::foo message2; ::foo message3 :: message1; ::foo message2; ::foo::bar message3 LOCATION AND FORMAT OF MESSAGE FILES Message files can be located in any directory, subject to the following conditions: [1] All message files for a package are in the same directory.[2] The message file name is a msgcat locale specifier (all lower-
case) followed by ``.msg''. For example:es.msg - spanish
engb.msg - United Kingdom English
[3] The file contains a series of calls to mmccsseett and mmccmmsseett, setting the necessary translation strings for the language, likely enclosed in a nnaammeessppaaccee eevvaall so that all source strings are tied to the namespace of the package. For example, a short eess..mmssgg might contain: namespace eval ::mypackage {::msgcat::mcset es "Free Beer!" "Cerveza Gracias!"
} RREECCOOMMMMEENNDDEEDD MMEESSSSAAGGEE SSEETTUUPP FFOORR PPAACCKKAAGGEESS If a package is installed into a subdirectory of the ttccllppkkggPPaatthh and loaded via ppaacckkaaggee rreeqquuiirree, the following procedure is recommended. [1] During package installation, create a subdirectory mmssggss under your package directory. [2] Copy your *.msg files into that directory. [3] Add the following command to your package initialization script:# load language files, stored in msgs subdirectory
::msgcat::mcload [file join [file dirname [info script]] msgs]
PPOOSSIITTIIOONNAALL CCOODDEESS FFOORR FFOORRMMAATT AANNDD SSCCAANN CCOOMMMMAANNDDSS It is possible that a message string used as an argument to ffoorrmmaatt might have positionally dependent parameters that might need to be repositioned. For example, it might be syntactically desirable to rearrange the sentence structure while translating.format "We produced %d units in location %s" $num $city
format "In location %s we produced %d units" $city $num
This can be handled by using the positional parameters:format "We produced %1\$d units in location %2\$s" $num $city
format "In location %2\$s we produced %1\$d units" $num $city
Similarly, positional parameters can be used with ssccaann to extract val-
ues from internationalized strings. CCRREEDDIITTSS The message catalog code was developed by Mark Harrison.SEE ALSO
format(n), scan(n), namespace(n), package(n) KKEEYYWWOORRDDSSinternationalization, i18n, localization, l10n, message, text, transla-
tionmsgcat 1.3 msgcat(n)