Provided by: liblog-report-perl_0.998-1_all bug

NAME

       Log::Report::Message - a piece of text to be translated

SYNOPSIS

        # Created by Log::Report's __ functions
        # Full feature description in the DETAILS section

        # no interpolation
        __"Hello, World";

        # with interpolation
        __x"age {years}", years => 12;

        # interpolation for one or many
        my $nr_files = @files;
        __nx"one file", "{_count} files", $nr_files;
        __nx"one file", "{_count} files", \@files;

        # interpolation of arrays
        __x"price-list: {prices%.2f}", prices => \@prices, _join => ', ';

        # white-spacing on msgid preserved
        print __"\tCongratulations,\n";
        print "\t", __("Congratulations,"), "\n";  # same

DESCRIPTION

       Any use of a translation function exported by Log::Report, like "__()" (the function is
       named underscore-underscore) or "__x()" (underscore-underscore-x) will result in this
       object.  It will capture some environmental information, and delay the translation until
       it is needed.

       Creating an object first and translating it later, is slower than translating it
       immediately.  However, on the location where the message is produced, we do not yet know
       in what language to translate it to: that depends on the front-end, the log dispatcher.

METHODS

   Constructors
       $obj->clone(OPTIONS, VARIABLES)
           Returns a new object which copies info from original, and updates it with the
           specified OPTIONS and VARIABLES.  The advantage is that the cached translations are
           shared between the objects.

           example: use of clone()

            my $s = __x "found {nr} files", nr => 5;
            my $t = $s->clone(nr => 3);
            my $t = $s->(nr => 3);      # equivalent
            print $s;     # found 5 files
            print $t;     # found 3 files

       Log::Report::Message->fromTemplateToolkit(DOMAIN, MSGID, PARAMS)
           See Log::Report::Extract::Template on the details how to integrate Log::Report
           translations with Template::Toolkit (version 1 and 2)

       Log::Report::Message->new(OPTIONS)
           End-users: do not use this method directly, but use Log::Report::__() and friends.
           The OPTIONS is a mixed list of object initiation parameters (all with a leading
           underscore) and variables to be filled in into the translated "_msgid" string.

            -Option   --Default
             _append    undef
             _category  undef
             _class     []
             _classes   []
             _count     undef
             _domain    <from "use Log::Report">
             _expand    false
             _join      $" $LIST_SEPARATOR
             _msgid     undef
             _plural    undef
             _prepend   undef
             _to        <undef>

           _append => STRING|MESSAGE
             Text as STRING or MESSAGE object to be displayed after the display of this message.

           _category => INTEGER
             The category when the real gettext library is used, for instance LC_MESSAGES.

           _class => STRING|ARRAY
             When messages are used for exception based programming, you add "_class" parameters
             to the argument list.  Later, with for instance
             Log::Report::Dispatcher::Try::wasFatal(class), you can check the category of the
             message.

             One message can be part of multiple classes.  The STRING is used as comma- and/or
             blank separated list of class tokens (barewords), the ARRAY lists all tokens
             separately. See classes().

           _classes => STRING|ARRAY
             Alternative for "_class", which cannot be used at the same time.

           _count => INTEGER|ARRAY|HASH
             When defined, the "_plural" need to be defined as well.  When an ARRAY is provided,
             the length of the ARRAY is taken.  When a HASH is given, the number of keys in the
             HASH is used.

           _domain => STRING
             The text-domain (translation table) to which this "_msgid" belongs.

             With this parameter, your can "borrow" translations from other textdomains.  Be very
             careful with this (although there are good use-cases)  The xgettext msgid extractor
             may add the used msgid to this namespace as well.  To avoid that, add a harmless
             '+':

               print __x(+"errors", _domain => 'global');

             The extractor will not take the msgid when it is an expression.  The '+' has no
             effect on the string at runtime.

           _expand => BOOLEAN
             Indicates whether variables are to be filled-in.

           _join => STRING
             Which STRING to be used then an ARRAY is being filled-in.

           _msgid => MSGID
             The message label, which refers to some translation information.  Usually a string
             which is close the English version of the message.  This will also be used if there
             is no translation possible/known.

             Leading white-space "\s" will be added to "_prepend".  Trailing white-space will be
             added before "_append".

           _plural => MSGID
             Can be used together with "_count".  This plural form of the "_msgid" text is used
             to simplify the work of translators, and as fallback when no translation is
             possible: therefore, this can best resemble an English message.

             White-space at the beginning and end of the string are stripped off.  The white-
             space provided by the "_msgid" will be used.

           _prepend => STRING|MESSAGE
             Text as STRING or MESSAGE object to be displayed before the display of this message.

           _to => NAME
             Specify the NAME of a dispatcher as destination explicitly. Short for  "report {to
             => NAME}, ..."  See to()

   Accessors
       $obj->append()
           Returns the string or Log::Report::Message object which is appended after this one.
           Usually "undef".

       $obj->classes()
           Returns the LIST of classes which are defined for this message; message group
           indicators, as often found in exception-based programming.

       $obj->count()
           Returns the count, which is used to select the translation alternatives.

       $obj->domain()
           Returns the domain of the first translatable string in the structure.

       $obj->msgid()
           Returns the msgid which will later be translated.

       $obj->prepend()
           Returns the string which is prepended to this one.  Usually "undef".

       $obj->to([NAME])
           Returns the NAME of a dispatcher if explicitly specified with the '_to' key. Can also
           be used to set it.  Usually, this will return undef, because usually all dispatchers
           get all messages.

       $obj->valueOf(PARAMETER)
           Lookup the named PARAMETER for the message.  All pre-defined names have their own
           method which should be used with preference.

           example:

           When the message was produced with

             my @files = qw/one two three/;
             my $msg = __xn "found one file: {file}"
                          , "found {nrfiles} files: {files}"
                          , scalar @files
                          , file    => $files[0]
                          , files   => \@files
                          , nrfiles => @files+0
                          , _class  => 'IO, files'
                          , _join   => ', ';

           then the values can be takes from the produced message as

             my $files = $msg->valueOf('files');  # returns ARRAY reference
             print @$files;              # 3
             my $count = $msg->count;    # 3
             my @class = $msg->classes;  # 'IO', 'files'
             if($msg->inClass('files'))  # true

           Simplified, the above example can also be written as:

             local $" = ', ';
             my $msg  = __xn "found one file: {files}"
                           , "found {_count} files: {files}"
                           , @files      # has scalar context
                           , files   => \@files
                           , _class  => 'IO, files';

   Processing
       $obj->concat(STRING|OBJECT, [PREPEND])
           This method implements the overloading of concatenation, which is needed to delay
           translations even longer.  When PREPEND is true, the STRING or OBJECT (other
           "Log::Report::Message") needs to prepended, otherwise it is appended.

           example: of concatenation

            print __"Hello" . ' ' . __"World!";
            print __("Hello")->concat(' ')->concat(__"World!")->concat("\n");

       $obj->inClass(CLASS|REGEX)
           Returns true if the message is in the specified CLASS (string) or matches the REGEX.
           The trueth value is the (first matching) class.

       $obj->toString([LOCALE])
           Translate a message.  If not specified, the default locale is used.

       $obj->untranslated()
           Return the concatenation of the prepend, msgid, and append strings.  Variable
           expansions within the msgid is not performed.

DETAILS

   OPTIONS and VARIABLES
       The Log::Report functions which define translation request can all have OPTIONS.  Some can
       have VARIABLES to be interpolated in the string as well.  To distinguish between the
       OPTIONS and VARIABLES (both a list of key-value pairs), the keys of the OPTIONS start with
       an underscore "_".  As result of this, please avoid the use of keys which start with an
       underscore in variable names.  On the other hand, you are allowed to interpolate OPTION
       values in your strings.

       Interpolating

       With the "__x()" or "__nx()", interpolation will take place on the translated MSGID
       string.  The translation can contain the VARIABLE and OPTION names between curly brackets.
       Text between curly brackets which is not a known parameter will be left untouched.

        fault __x"cannot open open {filename}", filename => $fn;

        print __xn"directory {dir} contains one file"
                 ,"directory {dir} contains {nr_files} files"
                 , scalar(@files)            # (1) (2)
                 , nr_files => scalar @files # (3)
                 , dir      => $dir;

       (1) this required third parameter is used to switch between the different plural forms.
       English has only two forms, but some languages have many more.

       (2) the "scalar" keyword is not needed, because the third parameter is in SCALAR context.
       You may also pass " \@files " there, because ARRAYs will be converted into their length.
       A HASH will be converted into the number of keys in the HASH.

       (3) the "scalar" keyword is required here, because it is LIST context: otherwise all
       filenames will be filled-in as parameters to "__xn()".  See below for the available
       "_count" valure, to see how the "nr_files" parameter can disappear.

       Interpolation of VARIABLES

       There is no way of checking beforehand whether you have provided all required values, to
       be interpolated in the translated string.

       For interpolating, the following rules apply:

       •   Simple scalar values are interpolated "as is"

       •   References to SCALARs will collect the value on the moment that the output is made.
           The "Log::Report::Message" object which is created with the "__xn" can be seen as a
           closure.  The translation can be reused.  See example below.

       •   Code references can be used to create the data "under fly".  The
           "Log::Report::Message" object which is being handled is passed as only argument.  This
           is a hash in which all OPTIONS and VARIABLES can be found.

       •   When the value is an ARRAY, all members will be interpolated with $" between the
           elements.  Alternatively (maybe nicer), you can pass an interpolation parameter via
           the "_join" OPTION.

        local $" = ', ';
        error __x"matching files: {files}", files => \@files;

        error __x"matching files: {files}", files => \@files, _join => ', ';

       Interpolating formatted

       Next to the name, you can specify a format code.  With "gettext()", you often see this:

        printf gettext("approx pi: %.6f\n"), PI;

       Locale::TextDomain has two ways.

        printf __"approx pi: %.6f\n", PI;
        print __x"approx pi: {approx}\n", approx => sprintf("%.6f", PI);

       The first does not respect the wish to be able to reorder the arguments during
       translation.  The second version is quite long.  With "Log::Report", above syntaxes do
       work, but you can also do

        print __x"approx pi: {pi%.6f}\n", pi => PI;

       So: the interpolation syntax is " { name [format] } ".  Other examples:

        print __x "{perms} {links%2d} {user%-8s} {size%10d} {fn}\n"
                , perms => '-rw-r--r--', links => 1, user => 'me'
                , size => '12345', fn => $filename;

       An additional advantage is the fact that not all languages produce comparable length
       strings.  Now, the translators can take care that the layout of tables is optimal.

       Interpolation of OPTIONS

       You are permitted the interpolate OPTION values in your string.  This may simplify your
       coding.  The useful names are:

       _msgid
           The MSGID as provided with Log::Report::__() and Log::Report::__x()

       _plural, _count
           The PLURAL MSGIDs, respectively the COUNT as used with Log::Report::__n() and
           Log::Report::__nx()

       _textdomain
           The label of the textdomain in which the translation takes place.

       _class or _classes
           Are to be used to group reports, and can be queried with inClass(),
           Log::Report::Exception::inClass(), or Log::Report::Dispatcher::Try::wasFatal().

       Handling white-spaces

       In above examples, the msgid and plural form have a trailing new-line.  In general, it is
       much easier to write

          print __x"Hello, World!\n";

       than

          print __x("Hello, World!") . "\n";

       For the translation tables, however, that trailing new-line is "over information"; it is
       an layout issue, not a translation issue.

       Therefore, the first form will automatically be translated into the second.  All leading
       and trailing white-space (blanks, new-lines, tabs, ...) are removed from the msgid befor
       the look-up, and then added to the translated string.

       Leading and trailing white-space on the plural form will also be removed.  However, after
       translation the spacing of the msgid will be used.

       Avoiding repetative translations

       This way of translating is somewhat expensive, because an object to handle the "__x()" is
       created each time.

        for my $i (1..100_000)
        {   print __x "Hello World {i}\n", i => $i;
        }

       The suggestion that Locale::TextDomain makes to improve performance, is to get the
       translation outside the loop, which only works without interpolation:

        use Locale::TextDomain;
        my $i = 42;
        my $s = __x("Hello World {i}\n", i => $i);
        foreach $i (1..100_000)
        {   print $s;
        }

       Oops, not what you mean.  With Log::Report, you can do it.

        use Log::Report;
        my $i;
        my $s = __x("Hello World {i}\n", i => \$i);
        foreach $i (1..100_000)
        {   print $s;
        }

       Mind you not to write: "for my $i" in above case!!!!

       You can also write an incomplete translation:

        use Log::Report;
        my $s = __x "Hello World {i}\n";
        foreach my $i (1..100_000)
        {   print $s->(i => $i);
        }

       In either case, the translation will be looked-up only once.

OVERLOADING

       overload: as function()
           When the object is used to call as function, a new object is created with the data
           from the original one but updated with the new parameters.  Implemented in "clone()".

       overload: concatenation()
           An (accidental) use of concatenation (a dot where a comma should be used) would
           immediately stringify the object.  This is avoided by overloading that operation.

       overload: stringification()
           When the object is used in string context, it will get translated.  Implemented as
           toString().

SEE ALSO

       This module is part of Log-Report distribution version 0.998, built on October 22, 2013.
       Website: http://perl.overmeer.net/log-report/

LICENSE

       Copyrights 2007-2013 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 http://www.perl.com/perl/misc/Artistic.html