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