# Objects 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
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.
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.
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.
Log::Report
uses String::Print to interpolate values in(translated)
messages. This is a very powerful syntax, and you should certainly read
that manual-page. Here, we only described additional features, specific
to the usage of String::Print
in Log::Report::Message
objects.
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:
Log::Report::Message
object which is created with
the __xn
can be seen as a closure. The translation can be reused.
See example below.
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.
$"
_join
OPTION.
local $" = ', '; error __x"matching files: {files}", files => \@files; error __x"matching files: {files}", files => \@files, _join => ', ';
You are permitted the interpolate OPTION values in your string. This may simplify your coding. The useful names are:
With Locale::TextDomain, you have to do
use Locale::TextDomain; print __nx ( "One file has been deleted.\n" , "{num} files have been deleted.\n" , $num_files , num => $num_files );
With Log::Report
, you can do
use Log::Report; print __nx ( "One file has been deleted.\n" , "{_count} files have been deleted.\n" , $num_files );
Of course, you need to be aware that the name used to reference the
counter is fixed to _count
. The first example works as well, but
is more verbose.
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 before 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.
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 because the first value of $i
is captured
in the initial message object. With Log::Report, you can do it (except
when you use contexts)
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.