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msgcat (1t)

Name

msgcat - Tcl message catalog

Synopsis

package require Tcl 8.5

package require msgcat 1.6

::msgcat::mc src-string ?arg arg ...?

::msgcat::mcmax ?src-string src-string ...?

::msgcat::mcexists ?-exactnamespace? ?-exactlocale? src-string          |

::msgcat::mclocale ?newLocale?

::msgcat::mcpreferences

::msgcat::mcloadedlocales subcommand ?locale?                           |

::msgcat::mcload dirname

::msgcat::mcset locale src-string ?translate-string?

::msgcat::mcmset locale src-trans-list

::msgcat::mcflset src-string ?translate-string?

::msgcat::mcflmset src-trans-list

::msgcat::mcunknown locale src-string ?arg arg ...?

::msgcat::mcpackagelocale subcommand ?locale?                           |

::msgcat::mcpackageconfig subcommand option ?value?                     |

::msgcat::mcforgetpackage

Description

msgcat(1t)                   Tcl Bundled Packages                   msgcat(1t)



______________________________________________________________________________

NAME
       msgcat - Tcl message catalog

SYNOPSIS
       package require Tcl 8.5

       package require msgcat 1.6

       ::msgcat::mc src-string ?arg arg ...?

       ::msgcat::mcmax ?src-string src-string ...?

       ::msgcat::mcexists ?-exactnamespace? ?-exactlocale? src-string          |

       ::msgcat::mclocale ?newLocale?

       ::msgcat::mcpreferences

       ::msgcat::mcloadedlocales subcommand ?locale?                           |

       ::msgcat::mcload dirname

       ::msgcat::mcset locale src-string ?translate-string?

       ::msgcat::mcmset locale src-trans-list

       ::msgcat::mcflset src-string ?translate-string?

       ::msgcat::mcflmset src-trans-list

       ::msgcat::mcunknown locale src-string ?arg arg ...?

       ::msgcat::mcpackagelocale subcommand ?locale?                           |

       ::msgcat::mcpackageconfig subcommand option ?value?                     |

       ::msgcat::mcforgetpackage
______________________________________________________________________________

DESCRIPTION
       The msgcat package provides a set of functions that can be used to man-
       age multi-lingual user interfaces.  Text strings are defined in a "mes-
       sage  catalog" which is independent from the application, and which can
       be edited or localized without modifying the application  source  code.
       New  languages  or  locales may be provided by adding a new file to the
       message catalog.

       msgcat distinguises packages by its namespace.  Each  package  has  its
       own message catalog and configuration settings in msgcat.

       A  locale  is  a  specification  string describing a user language like
       de_ch for Swiss German.  In msgcat, there is a global  locale  initial-
       ized  by  the  system  locale  of the current system.  Each package may
       decide to use the global locale or to use a package specific locale.

       The global locale may be changed on demand, for example by a user  ini-
       tiated  language  change  or within a multi user application like a web
       server.

COMMANDS
       ::msgcat::mc src-string ?arg arg ...?
              Returns a translation of src-string  according  to  the  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  applica-
              tion.   Instead of using an English string directly, an applica-
              tion 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::mcmax ?src-string src-string ...?
              Given several source strings, ::msgcat::mcmax 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).

       ::msgcat::mcexists ?-exactnamespace? ?-exactlocale? src-string
              Return true, if there is a translation for the given src-string. |

              The search may be limited by the option -exactnamespace to  only |
              check the current namespace and not any parent namespaces.       |

              It  may also be limited by the option -exactlocale to only check |
              the first prefered locale (e.g. first element returned by ::msg- |
              cat::mcpreferences if global locale is used).                    |

       ::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.   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 LOCALE SPECIFICATION  below
              for a description of the locale string format.

              If  the  locale is set, the preference list of locales is evalu- |
              ated.  Locales in this list are loaded now, if not jet loaded.

       ::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.   The  list  is  derived
              from the current locale set in msgcat by ::msgcat::mclocale, and
              cannot be set independently.  For example, if the current locale
              is    en_US_funky,    then    ::msgcat::mcpreferences    returns
              {en_us_funky en_us en {}}.

       ::msgcat:mcloadedlocales subcommand ?locale?
              This group of commands manage the list  of  loaded  locales  for
              packages not setting a package locale.

              The subcommand get returns the list of currently loaded locales.

              The  subcommand present requires the argument locale and returns
              true, if this locale is loaded.

              The subcommand clear removes all locales and their  data,  which
              are not in the current preference list.

       ::msgcat::mcload dirname
              Searches  the  specified directory for files that match the lan- |
              guage specifications returned by  ::msgcat::mcloadedlocales  get |
              (or  msgcat::mcpackagelocale  preferences if a package locale is |
              set) (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 message file either directly in their UTF-8 encoded form, or |
              by  use of the backslash-u quoting recognized by Tcl evaluation. |
              The number of message files which matched the specification  and |
              were loaded is returned.                                         |

              In  addition,  the  given folder is stored in the msgcat package |
              configuration option mcfolder to eventually load message catalog |
              files required by a locale change.

       ::msgcat::mcset 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.

       ::msgcat::mcmset 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
              ...?} ::msgcat::mcmset can be significantly faster than multiple
              invocations  of ::msgcat::mcset. The function returns the number
              of translations set.

       ::msgcat::mcflset src-string ?translate-string?
              Sets the translation for src-string to translate-string  in  the
              current namespace for the locale implied by the name of the mes-
              sage catalog being loaded via ::msgcat::mcload.   If  translate-
              string is not specified, src-string is used for both.  The func-
              tion returns translate-string.

       ::msgcat::mcflmset src-trans-list
              Sets the translation for multiple source strings  in  src-trans-
              list in the current namespace for the locale implied by the name
              of the message catalog being loaded via  ::msgcat::mcload.  src-
              trans-list  must  have  an even number of elements and is in the
              form {src-string translate-string  ?src-string  translate-string
              ...?} ::msgcat::mcflmset can be significantly faster than multi-
              ple invocations of ::msgcat::mcflset. The function  returns  the
              number of translations set.

       ::msgcat::mcunknown locale src-string ?arg arg ...?
              This routine is called by ::msgcat::mc 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 passed by format if there
              are any arguments.  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
              value of ::msgcat::mcunknown is used as the return value for the
              call to ::msgcat::mc.                                            |

              Note  that  this routine is only called if the concerned package |
              did not set a package locale unknown command name.               |

       ::msgcat::mcforgetpackage                                               |
              The calling package clears all its state within the msgcat pack- |
              age including all settings and translations.

LOCALE SPECIFICATION
       The  locale  is specified to msgcat by a locale string passed to ::msg-
       cat::mclocale.  The locale string  consists  of  a  language  code,  an
       optional 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 "en_US" specifies U.S. English.

       When the msgcat package is first  loaded,  the  locale  is  initialized
       according  to  the  user's  environment.   The  variables  env(LC_ALL),
       env(LC_MESSAGES), and env(LANG) are examined in order.   The  first  of
       them 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 ::msg-
       cat::mclocale with the argument

              language[_country][_modifier]

       On  Windows  and Cygwin, if none of those environment variables is set,
       msgcat will attempt to extract locale information  from  the  registry.
       From  Windows  Vista  on, the RFC4747 locale name "lang-script-country-
       options" is transformed to the locale as  "lang_country_script"  (Exam-
       ple:  sr-Latn-CS  ->  sr_cs_latin).  For Windows XP, the language id is
       transformed analoguously (Example: 0c1a  ->  sr_yu_cyrillic).   If  all
       these  attempts  to discover an initial locale from the user's environ-
       ment fail, 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
       en_GB_Funky, the locales "en_gb_funky", "en_gb", "en" and "" (the empty
       string)  are  searched  in order until a matching translation string is
       found.  If no translation string is available, then the unknown handler
       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.  It
       also allows the source string to be shorter and  less  prone  to  typo-
       graphical error.

       For example, executing the code

              ::msgcat::mcset en hello "hello from ::"
              namespace eval foo {
                  ::msgcat::mcset en hello "hello from ::foo"
              }
              puts [::msgcat::mc hello]
              namespace eval foo {puts [::msgcat::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  names-
       pace.

       For example, executing (in the "en" locale) the code

              ::msgcat::mcset en m1 ":: message1"
              ::msgcat::mcset en m2 ":: message2"
              ::msgcat::mcset en m3 ":: message3"
              namespace eval ::foo {
                  ::msgcat::mcset en m2 "::foo message2"
                  ::msgcat::mcset en m3 "::foo message3"
              }
              namespace eval ::foo::bar {
                  ::msgcat::mcset en m3 "::foo::bar message3"
              }
              namespace import ::msgcat::mc
              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
              en_gb.msg -- United Kingdom English

       Exception:   The  message  file  for  the  root  locale  ""  is  called
       "ROOT.msg".  This exception is made so as not to cause peculiar  behav-
       ior, such as marking the message file as "hidden" on Unix file systems.

       [3]    The  file  contains  a  series of calls to mcflset and mcflmset,
              setting the necessary  translation  strings  for  the  language,
              likely  enclosed  in a namespace eval so that all source strings
              are tied to the namespace of the package. For example,  a  short
              es.msg might contain:

              namespace eval ::mypackage {
                  ::msgcat::mcflset "Free Beer" "Cerveza Gratis"
              }

RECOMMENDED MESSAGE SETUP FOR PACKAGES
       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]

POSITIONAL CODES FOR FORMAT AND SCAN COMMANDS
       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  val-
       ues  from  internationalized  strings. Note that it is not necessary to
       pass the output of ::msgcat::mc to format directly; by passing the val-
       ues  to substitute in as arguments, the formatting substitution is done
       directly.

              msgcat::mc {Produced %1$d at %2$s} $num $city
              # ... where that key is mapped to one of the
              # human-oriented versions by msgcat::mcset

Package private locale                                                         |
       A package using msgcat may choose to use its own package private locale |
       and its own set of loaded locales, independent to the global locale set |
       by ::msgcat::mclocale.                                                  |

       This allows a package to change its locale without causing any  locales |
       load  or  removal in other packages and not to invoke the global locale |
       change callback (see below).                                            |

       This action is controled by the following ensemble:                     |

       ::msgcat::mcpackagelocale set ?locale?                                  |
              Set or change a package private  locale.   The  package  private |
              locale  is  set  to the given locale if the locale is given.  If |
              the option locale is not given, the package is  set  to  package |
              private  locale  mode,  but  no  locale  is changed (e.g. if the |
              global locale was valid for the package before, it is copied  to |
              the package private locale).                                     |

              This command may cause the load of locales.                      |

       ::msgcat::mcpackagelocale get                                           |
              Return  the  package  private locale or the global locale, if no |
              package private locale is set.                                   |

       ::msgcat::mcpackagelocale preferences                                   |
              Return the package private preferences  or  the  global  prefer- |
              ences, if no package private locale is set.                      |

       ::msgcat::mcpackagelocale loaded                                        |
              Return the list of locales loaded for this package.              |

       ::msgcat::mcpackagelocale isset                                         |
              Returns true, if a package private locale is set.                |

       ::msgcat::mcpackagelocale unset                                         |
              Unset  the  package  private  locale and use the globale locale. |
              Load and remove locales to adjust the list of loaded locales for |
              the package to the global loaded locales list.                   |

       ::msgcat::mcpackagelocale present locale                                |
              Returns true, if the given locale is loaded for the package.     |

       ::msgcat::mcpackagelocale clear                                         |
              Clear any loaded locales of the package not present in the pack- |
              age preferences.                                                 |

Changing package options                                                       |
       Each package using msgcat has a set  of  options  within  msgcat.   The |
       package options are described in the next sectionPackage options.  Each |
       package option may be set or unset  individually  using  the  following |
       ensemble:                                                               |

       ::msgcat::mcpackageconfig get option                                    |
              Return the current value of the given option.  This call returns |
              an error if the option is not set for the package.               |

       ::msgcat::mcpackageconfig isset option                                  |
              Returns 1, if the given option is set for the package, 0  other- |
              wise.                                                            |

       ::msgcat::mcpackageconfig set option value                              |
              Set  the given option to the given value.  This may invoke addi- |
              tional actions in dependency of the option.  The return value is |
              0 or the number of loaded packages for the option mcfolder.      |

       ::msgcat::mcpackageconfig unset option                                  |
              Unsets  the given option for the package.  No action is taken if |
              the option is not set for the  package.   The  empty  string  is |
              returned.                                                        |

   Package options                                                             |
       The following package options are available for each package:           |

       mcfolder                                                                |
              This is the message folder of the package. This option is set by |
              mcload and by the subcommand set. Both are  identical  and  both |
              return the number of loaded message catalog files.               |

              Setting  or  changing this value will load all locales contained |
              in the preferences valid for the package. This implies  also  to |
              invoke any set loadcmd (see below).                              |

              Unsetting  this  value  will  disable  message file load for the |
              package.                                                         |

       loadcmd                                                                 |
              This callback is invoked before a set of message  catalog  files |
              are loaded for the package which has this property set.          |

              This callback may be used to do any preparation work for message |
              file load or to get the message data from another source like  a |
              data  base. In this case, no message files are used (mcfolder is |
              unset).                                                          |

              See section  callback  invocation  below.   The  parameter  list |
              appended to this callback is the list of locales to load.        |

              If  this  callback is changed, it is called with the preferences |
              valid for the package.                                           |

       changecmd                                                               |
              This callback is invoked when a default local  change  was  per- |
              formed.  Its  purpose is to allow a package to update any depen- |
              dency on the default locale like showing the GUI in another lan- |
              guage.                                                           |

              See  the  callback invocation section below.  The parameter list |
              appended to this  callback  is  mcpreferences.   The  registered |
              callbacks are invoked in no particular order.                    |

       unknowncmd                                                              |
              Use a package locale mcunknown procedure instead of the standard |
              version supplied by the msgcat package (msgcat::mcunknown).      |

              The called procedure must return  the  formatted  message  which |
              will finally be returned by msgcat::mc.                          |

              A  generic  unknown  handler is used if set to the empty string. |
              This consists in returning the key if no  arguments  are  given. |
              With given arguments, format is used to process the arguments.   |

              See  section  callback invocation below.  The appended arguments |
              are identical to ::msgcat::mcunknown.                            |

   Callback invocation                                                         |
       A package  may  decide  to  register  one  or  multiple  callbacks,  as |
       described above.                                                        |

       Callbacks are invoked, if:                                              |

       1. the callback command is set,                                         |

       2. the command is not the empty string,                                 |

       3. the registering namespace exists.                                    |

       If  a  called  routine fails with an error, the bgerror routine for the |
       interpreter is invoked after command completion.  Only exception is the |
       callback  unknowncmd,  where an error causes the invoking mc-command to |
       fail with that error.                                                   |

   Examples                                                                    |
       Packages which display a GUI may update their widgets when  the  global |
       locale changes.  To register to a callback, use:                        |
              namespace eval gui {                                             |
                  msgcat::mcpackageconfig changecmd updateGUI                  |

                  proc updateGui args {                                        |
                      puts "New locale is '[lindex $args 0]'."                 |
                  }                                                            |
              }                                                                |
              % msgcat::mclocale fr                                            |
              fr                                                               |
              % New locale is 'fr'.                                            |

       If locales (or additional locales) are contained in another source like |
       a data base, a package may use the load callback and not mcload:        |
              namespace eval db {                                              |
                  msgcat::mcpackageconfig loadcmd loadMessages                 |

                  proc loadMessages args {                                     |
                      foreach locale $args {                                   |
                          if {[LocaleInDB $locale]} {                          |
                              msgcat::mcmset $locale [GetLocaleList $locale]   |
                          }                                                    |
                      }                                                        |
                  }                                                            |
              }                                                                |

       The clock command implementation uses msgcat with a package  locale  to |
       implement  the  command line parameter -locale.  Here are some sketches |
       of the implementation:                                                  |

       First, a package locale is initialized and the generic unknown function |
       is desactivated:                                                        |
              msgcat::mcpackagelocale set                                      |
              msgcat::mcpackageconfig unknowncmd ""                            |
       As  an  example,  the user requires the week day in a certain locale as |
       follows:                                                                |
              clock format clock seconds -format %A -locale fr                 |
       clock sets the package locale to fr and looks for the day name as  fol- |
       lows:                                                                   |
              msgcat::mcpackagelocale set $locale                              |
              return [lindex [msgcat::mc DAYS_OF_WEEK_FULL] $day]              |
              ### Returns "mercredi"                                           |
       Within  clock,  some message-catalog items are heavy in computation and |
       thus are dynamically cached using:                                      |
              proc ::tcl::clock::LocalizeFormat { locale format } {            |
                  set key FORMAT_$format                                       |
                  if { [::msgcat::mcexists -exactlocale -exactnamespace $key] } {|
                      return [mc $key]                                         |
                  }                                                            |
                  #...expensive computation of format clipped...               |
                  mcset $locale $key $format                                   |
                  return $format                                               |
              }                                                                |

CREDITS
       The message catalog code was developed by Mark Harrison.


ATTRIBUTES
       See attributes(7) for descriptions of the following attributes:


       +---------------+------------------+
       |ATTRIBUTE TYPE | ATTRIBUTE VALUE  |
       +---------------+------------------+
       |Availability   | runtime/tcl-8    |
       +---------------+------------------+
       |Stability      | Uncommitted      |
       +---------------+------------------+
SEE ALSO
       format(n), scan(n), namespace(n), package(n)

KEYWORDS
       internationalization, i18n, localization, l10n, message, text, transla-
       tion



NOTES
       This     software     was    built    from    source    available    at
       https://github.com/oracle/solaris-userland.   The  original   community
       source was downloaded from  http://prdownloads.sourceforge.net/tcl/tcl-
       core8.6.7-src.tar.gz

       Further information about this software can be found on the open source
       community website at https://www.tcl.tk/.



msgcat                                1.5                           msgcat(1t)