- NAME
- msgcat - Tcl message catalog
- SYNOPSIS
- ::msgcat::mc src-string
- ::msgcat::mclocale ?newLocale?
- ::msgcat::mcpreferences
- ::msgcat::mcload dirname
- ::msgcat::mcset locale src-string ?translate-string?
- ::msgcat::mcunknown locale src-string
- DESCRIPTION
- COMMANDS
- ::msgcat::mc src-string ?arg arg ...?
- ::msgcat::mclocale ?newLocale?
- ::msgcat::mcpreferences
- ::msgcat::mcload dirname
- ::msgcat::mcset locale src-string ?translate-string?
- ::msgcat::mcunknown locale src-string
- LOCALE AND SUBLOCALE SPECIFICATION
- NAMESPACES AND MESSAGE CATALOGS
- LOCATION AND FORMAT OF MESSAGE FILES
- RECOMMENDED MESSAGE SETUP FOR PACKAGES
- POSTITIONAL CODES FOR FORMAT AND SCAN COMMANDS
- CREDITS
- SEE ALSO
- KEYWORDS
msgcat - Tcl message catalog
::msgcat::mc src-string
::msgcat::mclocale ?newLocale?
::msgcat::mcpreferences
::msgcat::mcload dirname
::msgcat::mcset locale src-string ?translate-string?
::msgcat::mcunknown locale src-string
The msgcat package provides a set of functions
that can be used to manage 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 enabled for multi-lingual applications.
- ::msgcat::mc src-string ?arg arg ...?
-
Returns a translation of src-string according to the
user's current locale. If additional arguments past src-string
are given, the format command is used to substitute the
additional arguments in the translation of src-string.
::msgcat::mc will search the messages defined
in the current namespace 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, ::msgcat::mcunknown is called and the string
returned from ::msgcat::mcunknown is returned.
::msgcat::mc is the main function used to localize an
application. Instead of using an English string directly, an
applicaton can pass the English string through ::msgcat::mc and
use the result. If an application is written for a single language in
this fashion, then it is easy to add support for additional languages
later simply by defining new message catalog entries.
- ::msgcat::mclocale ?newLocale?
-
This function sets the locale to newLocale. If newLocale
is omitted, the current locale is returned, otherwise the current locale
is set to newLocale.
The initial locale defaults to the locale specified in
the user's environment. See LOCALE AND SUBLOCALE SPECIFICATION
below for a description of the locale string format.
- ::msgcat::mcpreferences
-
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. If the user has specified LANG=en_US_funky,
this procedure would return {en_US_funky en_US en}.
- ::msgcat::mcload dirname
-
Searches the specified directory for files that match
the language specifications returned by ::msgcat::mcpreferences.
Each file located is sourced. The file extension is ``.msg''.
The number of message files which matched the specification
and were loaded is returned.
- ::msgcat::mcset locale src-string ?translate-string?
-
Sets the translation for src-string to translate-string
in the specified locale. If translate-string is not
specified, src-string is used for both. The function
returns translate-string.
- ::msgcat::mcunknown locale src-string
-
This routine is called by ::msgcat::mc in the case when
a translation 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 ::msgcat::mcunknown procedure is invoked at the
same stack context as the call to ::msgcat::mc. The return vaue
of ::msgcat::mcunknown is used as the return vaue for the call
to ::msgcat::mc.
The locale is specified by a locale string.
The locale string consists of
a language code, an optional country code, and an optional
system-specific code, each separated by ``_''. The country and language
codes are specified in standards ISO-639 and ISO-3166.
For example, the locale ``en'' specifies English and
``en_US'' specifes U.S. English.
The locale defaults to the value in env(LANG) at the time the
msgcat package is loaded. If env(LANG) is not defined, then the
locale defaults to ``C''.
When a locale is specified by the user, a ``best match'' search is
performed during string translation. For example, if a user specifies
en_UK_Funky, the locales ``en_UK_Funky'', ``en_UK'', and ``en'' are
searched in order until a matching translation string is found. If no
translation string is available, then ::msgcat::unknown is
called.
Strings stored in the message catalog are stored relative
to the namespace from which they were added. This allows
multiple packages to use the same strings without fear
of collisions with other packages. It also allows the
source string to be shorter and less prone to typographical
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. This allows child namespaces
to "inherit" messages from their parent namespace.
For example, executing 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
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 locale specifier followed
by ``.msg''. For example:
es.msg -- spanish
en_UK.msg -- UK English
- [3]
-
The file contains a series of calls to mcset, setting the
necessary translation strings for the language. For example:
::msgcat::mcset es "Free Beer!" "Cerveza Gracias!"
If a package is installed into a subdirectory of the
tcl_pkgPath and loaded via package require, the
following procedure is recommended.
- [1]
-
During package installation, create a subdirectory
msgs 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]
It is possible that a message string used as an argument
to format 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 scan to
extract values from internationalized strings.
The message catalog code was developed by Mark Harrison.
format, scan, namespace, package
internationalization, i18n, localization, l10n, message, text, translation
Copyright © 1998 Mark Harrison.
Copyright © 1995-1997 Roger E. Critchlow Jr.