Provided by: libintl-perl_1.33-1build3_all 
NAME
Locale::Messages - Gettext Like Message Retrieval
SYNOPSIS
use Locale::Messages qw(:locale_h :libintl_h);
gettext $msgid;
dgettext $textdomain, $msgid;
dcgettext $textdomain, $msgid, LC_MESSAGES;
ngettext $msgid, $msgid_plural, $count;
dngettext $textdomain, $msgid, $msgid_plural, $count;
dcngettext $textdomain, $msgid, $msgid_plural, $count, LC_MESSAGES;
pgettext $msgctxt, $msgid;
dpgettext $textdomain, $msgctxt, $msgid;
dcpgettext $textdomain, $msgctxt, $msgid, LC_MESSAGES;
npgettext $msgctxt, $msgid, $msgid_plural, $count;
dnpgettext $textdomain, $msgctxt, $msgid, $msgid_plural, $count;
dcnpgettext $textdomain, $msgctxt, $msgid, $msgid_plural, $count, LC_MESSAGES;
textdomain $textdomain;
bindtextdomain $textdomain, $directory;
bind_textdomain_codeset $textdomain, $encoding;
bind_textdomain_filter $textdomain, \&filter, $data;
turn_utf_8_on ($variable);
turn_utf_8_off ($variable);
nl_putenv ('OUTPUT_CHARSET=koi8-r');
my $category = LC_CTYPE;
my $category = LC_NUMERIC;
my $category = LC_TIME;
my $category = LC_COLLATE;
my $category = LC_MONETARY;
my $category = LC_MESSAGES;
my $category = LC_ALL;
DESCRIPTION
The module Locale::Messages is a wrapper around the interface to message translation
according to the Uniforum approach that is for example used in GNU gettext and Sun's
Solaris. It is intended to allow Locale::Messages(3) to switch between different
implementations of the lower level libraries but this is not yet implemented.
Normally you should not use this module directly, but the high level interface
Locale::TextDomain(3) that provides a much simpler interface. This description is
therefore deliberately kept brief. Please refer to the GNU gettext documentation
available at <http://www.gnu.org/manual/gettext/> for in-depth and background information
on the topic.
The lower level module Locale::gettext_pp(3) provides the Perl implementation of gettext()
and related functions.
FUNCTIONS
The module exports by default nothing. Every function has to be imported explicitly or
via an export tag ("EXPORT TAGS").
gettext MSGID
Returns the translation for MSGID. Example:
print gettext "Hello World!\n";
If no translation can be found, the unmodified MSGID is returned, i. e. the function
can never fail, and will never mess up your original message.
Note for Perl 5.6 and later: The returned string will always have the UTF-8 flag off
by default. See the documentation for function bind_textdomain_filter() for a way to
change this behavior.
One common mistake is this:
print gettext "Hello $name!";
Perl will interpolate the variable $name before the function will see the string.
Unless the corresponding message catalog contains a message "Hello Tom!", "Hello
Dick!" or "Hello Harry!", no translation will be found.
Using printf() and friends has its own problems:
print sprintf (gettext ("This is the %s %s."), $color, $thing);
(The example is stupid because neither color nor thing will get translated here ...).
In English the adjective (the color) will precede the noun, many other languages (for
example French or Italian) differ here. The translator of the message may therefore
have a hard time to find a translation that will still work and not sound stupid in
the target language. Many C implementations of printf() allow one to change the order
of the arguments, and a French translator could then say:
"C'est le %2$s %1$s."
Perl printf() implements this feature as of version 5.8 or better. Consequently you
can only use it, if you are sure that your software will run with Perl 5.8 or a later
version.
Another disadvantage of using printf() is its cryptic syntax (maybe not for you but
translators of your software may have their own opinion).
See the description of the function "__x()" in Locale::TextDomain(3) for a much better
way to get around this problem.
Non-ASCII message ids ...
You should note that the function (and all other similar functions in this module)
does a bytewise comparison of the MSGID for the lookup in the translation catalog, no
matter whether obscure utf-8 flags are set on it, whether the string looks like utf-8,
whether the utf8(3pm) pragma is used, or whatever other weird method past or future
perl(1) versions invent for guessing character sets of strings.
Using other than us-ascii characters in Perl source code is a call for trouble, a
compatibility nightmare. Furthermore, GNU gettext only lately introduced support for
non-ascii character sets in sources, and support for this feature may not be available
everywhere. If you absolutely want to use MSGIDs in non-ascii character sets, it is
wise to choose utf-8. This will minimize the risk that perl(1) itself will mess with
the strings, and it will also be a guaranty that you can later translate your project
into arbitrary target languages.
Other character sets can theoretically work. Yet, using another character set in the
Perl source code than the one used in your message catalogs will never work, since the
lookup is done bytewise, and all strings with non-ascii characters will not be found.
Even if you have solved all these problems, there is still one show stopper left: The
gettext runtime API lacks a possibility to specify the character set of the source
code (including the original strings). Consequently - in absence of a hint for the
input encoding - strings without a translation are not subject to output character set
conversion. In other words: If the (non-determinable) output character set differs
from the character set used in the source code, output can be a mixture of two
character sets. There is no point in trying to address this problem in the pure Perl
version of the gettext functions. because breaking compatibility between the Perl and
the C version is a price too high to pay.
This all boils down to: Only use ASCII characters in your translatable strings!
dgettext TEXTDOMAIN, MSGID
Like gettext(), but retrieves the message for the specified TEXTDOMAIN instead of the
default domain. In case you wonder what a textdomain is, you should really read on
with Locale::TextDomain(3).
dcgettext TEXTDOMAIN, MSGID, CATEGORY
Like dgettext() but retrieves the message from the specified CATEGORY instead of the
default category "LC_MESSAGES".
ngettext MSGID, MSGID_PLURAL, COUNT
Retrieves the correct translation for COUNT items. In legacy software you will often
find something like:
print "$count file(s) deleted.\n";
or
printf "$count file%s deleted.\n", $count == 1 ? '' : 's';
The first example looks awkward, the second will only work in English and languages
with similar plural rules. Before ngettext() was introduced, the best practice for
internationalized programs was:
if ($count == 1) {
print gettext "One file deleted.\n";
} else {
printf gettext "%d files deleted.\n";
}
This is a nuisance for the programmer and often still not sufficient for an adequate
translation. Many languages have completely different ideas on numerals. Some
(French, Italian, ...) treat 0 and 1 alike, others make no distinction at all
(Japanese, Korean, Chinese, ...), others have two or more plural forms (Russian,
Latvian, Czech, Polish, ...). The solution is:
printf (ngettext ("One file deleted.\n",
"%d files deleted.\n",
$count), # argument to ngettext!
$count); # argument to printf!
In English, or if no translation can be found, the first argument (MSGID) is picked if
$count is one, the second one otherwise. For other languages, the correct plural form
(of 1, 2, 3, 4, ...) is automatically picked, too. You don't have to know anything
about the plural rules in the target language, ngettext() will take care of that.
This is most of the time sufficient but you will have to prove your creativity in
cases like
printf "%d file(s) deleted, and %d file(s) created.\n";
dngettext TEXTDOMAIN, MSGID, MSGID_PLURAL, COUNT
Like ngettext() but retrieves the translation from the specified textdomain instead of
the default domain.
dcngettext TEXTDOMAIN, MSGID, MSGID_PLURAL, COUNT, CATEGORY
Like dngettext() but retrieves the translation from the specified category, instead of
the default category "LC_MESSAGES".
pgettext MSGCTXT, MSGID
Returns the translation of MSGID, given the context of MSGCTXT.
Both items are used as a unique key into the message catalog.
This allows the translator to have two entries for words that may translate to
different foreign words based on their context. For example, the word "View" may be a
noun or a verb, which may be used in a menu as File->View or View->Source.
pgettext "Verb: To View", "View\n";
pgettext "Noun: A View", "View\n";
The above will both lookup different entries in the message catalog.
A typical usage are GUI programs. Imagine a program with a main menu and the
notorious "Open" entry in the "File" menu. Now imagine, there is another menu entry
Preferences->Advanced->Policy where you have a choice between the alternatives "Open"
and "Closed". In English, "Open" is the adequate text at both places. In other
languages, it is very likely that you need two different translations. Therefore, you
would now write:
pgettext "File|", "Open";
pgettext "Preferences|Advanced|Policy", "Open";
In English, or if no translation can be found, the second argument (MSGID) is
returned.
The function was introduced with libintl-perl version 1.17.
dpgettext TEXTDOMAIN, MSGCTXT, MSGID
Like pgettext(), but retrieves the message for the specified TEXTDOMAIN instead of the
default domain.
The function was introduced with libintl-perl version 1.17.
dcpgettext TEXTDOMAIN, MSGCTXT, MSGID, CATEGORY
Like dpgettext() but retrieves the message from the specified CATEGORY instead of the
default category "LC_MESSAGES".
The function was introduced with libintl-perl version 1.17.
npgettext MSGCTXT, MSGID, MSGID_PLURAL, COUNT
Like ngettext() with the addition of context as in pgettext().
In English, or if no translation can be found, the second argument (MSGID) is picked
if $count is one, the third one otherwise.
The function was introduced with libintl-perl version 1.17.
dnpgettext TEXTDOMAIN, MSGCTXT, MSGID, MSGID_PLURAL, COUNT
Like npgettext() but retrieves the translation from the specified textdomain instead
of the default domain.
The function was introduced with libintl-perl version 1.17.
dcnpgettext TEXTDOMAIN, MSGCTXT, MSGID, MSGID_PLURAL, COUNT, CATEGORY
Like dnpgettext() but retrieves the translation from the specified category, instead
of the default category "LC_MESSAGES".
The function was introduced with libintl-perl version 1.17.
textdomain TEXTDOMAIN
Sets the default textdomain (initially 'messages').
bindtextdomain TEXTDOMAIN, DIRECTORY
Binds TEXTDOMAIN to DIRECTORY. Huh? An example:
bindtextdomain "my-package", "./mylocale";
Say, the selected locale (actually the selected locale for category "LC_MESSAGES") of
the program is 'fr_CH', then the message catalog will be expected in
./mylocale/fr_CH/LC_MESSAGES/my-package.mo.
bind_textdomain_codeset TEXTDOMAIN, ENCODING
Sets the output encoding for TEXTDOMAIN to ENCODING.
bind_textdomain_filter TEXTDOMAN, CODEREF, DATA
bind_textdomain_filter TEXTDOMAN, CODEREF
By default, Locale::Messages will turn the utf-8 flag of all returned messages off.
If you want to change this behavior, you can pass a reference to a subroutine that
does different things - for example turn the utf-8 flag on, or leave it untouched.
The callback function will be called with DATA as the first, and the possibly
translated string as the second argument. It should return the possibly modified
string.
If you want an object method to be called, pass the object itself in the data
parameter and write a wrapper function. Example:
sub wrapper {
my ($string, $obj) = @_;
$obj->filterMethod ($string);
}
my $obj = MyPackage->new;
bind_textdomain_filter ('mydomain', \&wrapper, $obj);
The function cannot fail and always returns a true value.
Attention: If you use the function for setting the utf-8 flag, it is your
responsibility to ensure that the output is really utf-8. You should only use it, if
you have set the environment variable OUTPUT_CHARSET to "utf-8". Additionally you
should call bind_textdomain_codeset() with "utf-8" as the second argument.
Steven Haryanto has written a module Locale::TextDomain::UTF8(3pm) that addresses the
same problem.
This function has been introduced in libintl-perl 1.16 and it is not part of the
standard gettext API.
turn_utf_8_on VARIABLE
Returns VARIABLE but with the UTF-8 flag (only known in Perl >=5.6) guaranteed to be
turned on. This function does not really fit into the module, but it is often handy
nevertheless.
The flag does not mean that the string is in fact valid utf-8!
The function was introduced with libintl-perl version 1.16.
turn_utf_8_off VARIABLE
Returns VARIABLE but with the UTF-8 flag (only known in Perl >=5.6) guaranteed to be
turned off. This function does not really fit into the module, but it is often handy
nevertheless.
The function was introduced with libintl-perl version 1.07.
select_package PACKAGE
By default, Locale::Messages will try to load the XS version of the gettext
implementation, i. e. Locale::gettext_xs(3) and will fall back to the pure Perl
implementation Locale::gettext_pp(3). You can override this behavior by passing the
string "gettext_pp" or "gettext_xs" to the function select_package(). Passing
"gettext_pp" here, will prefer the pure Perl implementation.
You will normally want to use that in a BEGIN block of your main script.
The function was introduced with libintl-perl version 1.03 and is not part of the
standard gettext API.
Beginning with version 1.22 you can pass other package names than "gettext_pp" or
"gettext_xs" and use a completely different backend. It is the caller's
responsibility to make sure that the selected package offers the same interface as the
two standard packages.
One package that offers that functionality is Locale::gettext_dumb(3pm).
nl_putenv ENVSPEC
Resembles the ANSI C putenv(3) function. The sole purpose of this function is to work
around some ideosyncrasies in the environment processing of Windows systems. If you
want to portably set or unset environment variables, use this function instead of
directly manipulating %ENV.
The argument ENVSPEC may have three different forms.
LANGUAGE=fr_CH
This would set the environment variable "LANGUAGE" to "fr_CH".
LANGUAGE=
Normally, this will set the environment variable "LANGUAGE" to an empty
string. Under Windows, however, the environment variable will be deleted
instead (and is no longer present in %ENV). Since within libintl-perl empty
environment variables are useless, consider this usage as deprecated.
LANGUAGE
This will delete the environment variable LANGUAGE. If you are familiar with
the brain-damaged implementation of putenv(3) (resp. _putenv()) in the so-
called standard C library of MS-Windows, you may suspect that this is an
invalid argument. This is not the case! Passing a variable name not followed
by an equal sign will always delete the variable, no matter which operating
system you use.
The function returns true for success, and false for failure. Possible reasons for
failure are an invalid syntax or - only under Windows - failure to allocate space for
the new environment entry ($! will be set accordingly in this case).
Why all this hassle? The 32-bit versions of MS-DOS (currently Windows
95/98/ME/NT/2000/XP/CE/.NET) maintain two distinct blocks of environment variables per
process. Which block is considered the "correct" environment is a compile-time option
of the Perl interpreter. Unfortunately, if you have build the XS version
Locale::gettext_xs(3) under Windows, the underlying library may use a different
environment block, and changes you make to %ENV may not be visible to the library.
The function nl_putenv() is mostly a funny way of saying
LANGUAGE=some_value
but it does its best, to pass this information to the gettext library. Under other
operating systems than Windows, it only operates on %ENV, under Windows it will call
the C library function _putenv() (after doing some cleanup to its arguments), before
manipulating %ENV.
Please note, that your %ENV is updated by nl_putenv() automatically.
The function has been introduced in libintl-perl version 1.10.
setlocale
Modifies and queries program's locale, see the documentation for setlocale() in
POSIX(3pm) instead.
On some systems, when using GNU gettext, a call from C to setlocale() is - with the
help of the C preprocessor - really a call to libintl_setlocale(), which is in turn a
wrapper around the system setlocale(3). Failure to call libintl_setlocale() may lead
to certain malfunctions. On such systems, Locale::Messages::setlocale() will call the
wrapper libintl_setlocale(). If you want to avoid problems, you should therefore
always call the setlocale() implementation in Locale::Messages(3pm).
See <https://rt.cpan.org/Public/Bug/Display.html?id=83980> or
<https://savannah.gnu.org/bugs/?38162>, and
<https://savannah.gnu.org/bugs/?func=detailitem&item_id=44645> for a discussion of the
problem.
The function has been introduced in libintl-perl version 1.24.
CONSTANTS
You can (maybe) get the same constants from POSIX(3); see there for a detailed description
LC_CTYPE
LC_NUMERIC
LC_TIME
LC_COLLATE
LC_MONETARY
LC_MESSAGES
This locale category was the reason that these constants from POSIX(3) were included
here. Even if it was present in your systems C include file locale.h, it was not
provided by POSIX(3). Perl 5.8 and later seems to export the constant if available,
although it is not documented in POSIX(3).
Locale::Messages(3) makes an attempt to guess the value of this category for all
systems, and assumes the arbitrary value 1729 otherwise.
LC_ALL
If you specify the category LC_ALL as the first argument to POSIX::setlocale(), all
locale categories will be affected at once.
EXPORT TAGS
The module does not export anything unless explicitly requested. You can import groups of
functions via two tags:
use Locale::Messages (':locale_h')
Imports the functions that are normally defined in the C include file locale.h:
gettext()
dgettext()
dcgettext()
ngettext()
dngettext()
dcngettext()
pgettext()
dpgettext()
dcpgettext()
npgettext()
dnpgettext()
dcnpgettext()
textdomain()
bindtextdomain()
bind_textdomain_codeset()
use Locale::Messages (':libintl_h')
Imports the locale category constants:
LC_CTYPE
LC_NUMERIC
LC_TIME
LC_COLLATE
LC_MONETARY
LC_MESSAGES
LC_ALL
OTHER EXPORTS
select_package PACKAGE
USAGE
A complete example:
1: use Locale::Messages qw(:locale_h :libintl_h);
2: use POSIX qw (setlocale);
3: setlocale (LC_MESSAGES, '');
4: textdomain ('my-package');
5: bindtextdomain ('my-package' => '/usr/local/share/locale');
6:
7: print gettext ("Hello world!\n");
Step by step: Line 1 imports the necessary functions and constants. In line 3 we set the
locale for category LC_MESSAGES to the default user settings. For C programs you will
often read that LC_ALL is the best category here but this will also change the locale for
LC_NUMERIC and many programs will not work reliably after changing that category in Perl;
choose your own poison!
In line 4 we say that all messages (translations) without an explicit domain specification
should be retrieved from the message catalog for the domain 'my-package'. Line 5 has the
effect that the message catalog will be searched under the directory
/usr/local/share/locale.
If the user has selected the locale 'fr_CH', and if the file
/usr/local/share/locale/fr_CH/LC_MESSAGES/my-package.mo exists, and if it contains a GNU
message object file with a translation for the string "Hello world!\n", then line 7 will
print the French translation (for Switzerland CH) to STDOUT.
The documentation for GNU gettext explains how to extract translatable strings from your
Perl files and how to create message catalogs.
Another less portable example: If your system uses the GNU libc you should be able to find
various files with the name libc.mo, the message catalog for the library itself. If you
have found these files under /usr/share/locale, then you can try the following:
use Locale::Messages qw(:locale_h :libintl_h);
use POSIX qw (setlocale);
setlocale LC_MESSAGES, "";
textdomain "libc";
# The following is actually not needed, since this is
# one of the default search directories.
bindtextdomain libc => '/usr/share/locale';
bind_textdomain_codeset libc => 'iso-8859-1';
print gettext ("No such file or directory");
See Locale::TextDomain(3) for much simpler ways.
AUTHOR
Copyright (C) 2002-2017 Guido Flohr <http://www.guido-flohr.net/>
(<mailto:guido.flohr@cantanea.com>), all rights reserved. See the source code for
details!code for details!
SEE ALSO
Locale::TextDomain(3pm), Locale::gettext_pp(3pm), Encode(3pm), perllocale(3pm),
POSIX(3pm), perl(1), gettext(1), gettext(3)