Mark Overmeer > Log-Report-Lexicon-1.03 > Log::Report::Translator::Context



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Log::Report::Translator::Context - handle translation contexts


  # usually, the context information is in a separate file
  textdomain 'my-domain'
    , config => $filename;


[Added in Log::Report v1.00] The "contexts" concept in (GNU's version of) gettext, has a very restricted purpose: to separate two (accidental) uses of the same message-id, under different circumstances. The same msgid may translated diffently in one file or the other. The name "context" is pretending much more power than the gettext libraries are capable of: it only behaves like a namespace.

For Log::Report, the power of "context" is extended with selecting between alternatives for the use of a msgid on the same spot. For instance, the gender of the user of the website determines whether `he' or `she' needs to be used in the translation. In this example, the gender is set as context keyword in the message:

   my ($name, $gender) = ('Jack', 'male');
   print __x"{name<gender} found his key", name => $name
     , _context => $gender;



  rules   {}
rules => HASH



Returns a HASH to the simplified context maps.


$obj->ctxtFor( $message, $lang, [$context] )

Returns a pair of the MSGID stripped from context markup, and the context evaluated into the msgctxt string. The $message is a Log::Report::Message object. The $context is the default context for a certain textdomain.

  my ($msgid, $msgctxt) = $context->ctxtFor($msg, $lang, $context);
$obj->expand($msgid, $language, %options)

Expand the context settings into all possible combinations which need translations in the PO file. This may depend on the $language. The $msgid is used in error messages.

$obj->needDecode($source, STRING|ARRAY|HASH|LIST)
Log::Report::Translator::Context->needDecode($source, STRING|ARRAY|HASH|LIST)

Converts the context settings passed with the MSGID, into a HASH which will be matched to the context providers.


Using context_rules

In Log::Report's extended concept of "contexts", you can select between multiple translations for the same msgid, when they

In the standard gettext set-up, some msgid may accidentally collide between two different uses. For instance, whether you translate the word "Open" in the menu for "Files" to mean "open a file", and the word "Open" in the status display meaning "the file is open". In some languages, these translations may differ. Using a msgctxt keyword will cause the same msgid to appear twice in the PO-file.

But, there is a much broader need for context sensitive translations, which is not in the provided by standard gettext: environmental information or parameters may influence the translation more than simply solvable by inserted parameters.

For instance, the gender of the user of the website determines whether `he' or `she' needs to be used. In this example, the gender is set as context keyword in the message:

   $name = 'Jack';
   print __x"{name} found her key", name => $name;

You may try to solve this via:

   my ($name, $gender) = ('Jack', 'male');
   print __x"{name} found {personal} key", name => $name
     , personal => ($gender eq 'male' ? 'his' : 'her');    # No!

This does not translate! For one, you would need to translate his and her to the language as well. But in some languages, the differences between addressed genders have more impact on the whole sentence.

So, Log::Report translations add extra syntax:

   my ($name, $gender) = ('Jack', 'male');
   print __x"{name<gender} found her key", name => $name
     , _context => "gender=$gender";

The gender marking tells the translation table builder (xgettext-perl) and the translation handler that there is a context active.

Now, the English PO-file has

   # gender alternatives 'male' and 'female'

   msgctxt "gender=male"
   msgid  "{name} found his key"
   msgstr "{name} found his key"

   msgctxt "gender=female"
   msgid   "{name} found his key"
   msgstr  "{name} found her key"

To make this work, both the application and the xgettext-perl script must share information to understand which genders are available. See the section on "Configuration" below.

Another example:

   print __x"greetings{<style}";
   # style alternatives 'formal' and 'informal'

   msgctxt "style=formal"
   msgid   "greetings"
   msgstr  "Dear Sir/Madam,"

   msgctxt "style=informal"
   msgid   "greetings"
   msgstr  "Hey buddy,"

As can be seen, the '<style' marking may be added inside the '{}' of a filled-in parameter, or may appear on its own. These markings are removed from the msgid in the PO file, so that you may freely add them to the strings used in your program without disturbing existing translations.

Specifying the context per Message

You need to specify the context at each message which is influenced by the context. This can be a comma separated list of words, an ARRAY, or a HASH:

  _context => 'gender=male'
  _context => 'gender=male,agegroup=adult,married=yes'
  _context => [ 'gender=male', 'agegroup=adult', 'married=yes']
  _context => [ qw/gender=male agegroup=adult married=yes/ ]

  my @context = (qw/gender=male agegroup=adult married=yes/);
  _context => \@context;

Probably the my %context = (gender => 'male', agegroup => 'adult', married => 'yes'); my %context = qw/gender male agegroup adult married yes/; _context => \%context;

Standard gettext only allows a single keyword (=string) Log::Report permits you to set-up a context for a whole text-domain, which means that multiple context rules may be active at any moment.

Specifying the context per Domain

Above examples are to be specified per message. You may also set a default. The top of your modules set the text-domain (name of the translation table) for all strings found in those files. In this case, for instance "webpages"

  # Log::Report::textdomain()
  (textdomain 'webpages')->setContext(%context);

This context is used as defaults, the _context attribute used by strings are overruling these.

The msgctxt

The gnutext implementation of the context is very simple. This is to be expected from a library written in C. The msgctxt alternatives are matched against the context keywords of the message. In all or none of the alternatives match, then just a random translation is choosen.

In the simplest form, the msgctxt field contains a single keyword (not containing a comma).

   msgctxt "gender=male"

But you can do more. Be warned that most (all?) existing tools which smartly edit PO-files do not understand these constructs: they see the msgctxt as dump string without meaning.

   msgctxt "agegroup=baby,agegroup=grandparent" # baby OR grandparent
   msgctxt "gender=male agegroup=adult"         # both male AND adult

So, a comma separated list of alternatives. If any matches, then the rule is selected.


The tools which handle translations expect the msgctxt to be static. For instance, contain a filename where the string is used to disambigue accidental collissions of the use of the same msgid for different purposes.

Now, we have designed far more flexible contexts. We need to generate all possible msgctxt values while extracting msgids to update the PO-files. Therefore, we need a map-file.

The context maps are included in a configuration file which is passed to xgettext-perl and to the program which uses contexts. See Log::Report::Domain::readConfig().

Example of such configuration file: (JSON syntax and Perl syntax)

  === JSON ===                    ==== Perl ===
  {                               {
     "context_rules" : {             context_rules => {
        "gender" : [                    gender => [
           "male",                         'male',
           "female"                        'female'
        ]                               ]
     }                               }
  }                               }


  {                               {
     "context_rules" : {             context_rules => {
        "gender" : {                    gender => {
           "alternatives" : [              alternatives => [
              "male",                         'male',
              "female",                       'female',
              "unknown"                       'unknown'
           ]                               ]
           ... more config for 'gender'    ...
        }                                }
     }                               }
  }                               }

As "alternatives", we list the alternatives as known by the application internals. Each msgid which contains a {<gender} mark will be replicated three times, in each language table. Each copy will be marked with a different value from "alternatives".

However, languages differ. For instance, in some language we may address the unknown gender as being a male person. In other languages, the translation can express this "unknown" personality. To get this to work, you can use the msgctxt construct.

The default msgctxt, as used in the previous example, is simply mapping the alternatives directly on msgctxt values which are the same:

  {                                { context_rules =>
   "context_rules" : {                { gender =>
      "gender" : {                      { default => { qw/
         "default" : {                      female  female
            "female" : "female",            male    male
            "male" : "male"                 unknown male / }
            "unknown" : "male",         , 'nl,de' => { qw/
         },                                 unknown x    / }
         "nl,de" : {
            "unknown" : "x"
         }                              }
       ... more configuration ...
    ... more context rules ...
    }                                 }
  }                                }

By default, there will only be two msgid copies in a language file, because at run-time the "unknown" is mapped on "male". An exception for the Dutch (nl*) and German (de*) tables, which apparently support the third gender.

If you are not interested for a certain tag, then put it on 'IGNORE' as default or for your language.

         "default" : "IGNORE",           default => 'IGNORE'
         "nl": "IGNORE"                  nl => 'IGNORE'


This module is part of Log-Report-Lexicon distribution version 1.03, built on June 04, 2014. Website:


Copyrights 2007-2014 by [Mark Overmeer]. For other contributors see ChangeLog.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. See

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