Locale::Wolowitz - Dead simple localization with JSON.


        # in ./i18n/locales.coll.json
                "Welcome!": {
                        "he": "ברוכים הבאים!",
                        "es": "Bienvenido!"
                "I'm using %1": {
                        "he": "אני משתמש ב%1",
                        "es": "Estoy usando %1"
                "Linux": {
                        "he": "לינוקס"

        # in your app
        use Locale::Wolowitz;

        my $w = Locale::Wolowitz->new( './i18n' );

        print $w->loc('Welcome!', 'es'); # prints 'Bienvenido!'

        print $w->loc("I'm using %1", 'he', $w->loc('Linux', 'he')); # prints "אני משתמש בלינוקס"

        # you can also directly load data (useful if data is not in files, but say in database)
                hello => {
                        he => 'שלום',
                        fr => 'bonjour'

        print $w->loc('hello', 'he'); # prints "שלום"


Locale::Wolowitz is a very simple text localization system. Yes, another localization system.

Frankly, I never realized how to use the standard Perl localization systems such as Locale::Maketext, Gettext, Data::Localize or whatever. It seems they are more meant to localize an application to the language of the system on which its running, which isn't really what I need. Most of the time, seeing as how I'm mostly writing web applications, I wish to localize my applications/websites according to the user's wishes, not by the system. For example, I may create a content management system where the user can select the interface's language. Also, I grew to hate the standard .po files, and thought using a JSON format might be more comfortable.

Locale::Wolowitz allows you to provide different languages to end-users of your applications. To some extent, when writing RESTful web applications, this means you can perform language negotiation with visitors (see Content negotiation on Wikipedia).

Locale::Wolowitz works with JSON files. Each file can serve one or more languages. When creating an instance of this module, you are required to pass a path to a directory where your application's JSON localization files are present. These are all loaded and merged into one big hash-ref (unless you tell the module to only load a specific file), which is stored in memory. A file with only one language has to be named <lang>.json (where <lang> is the name of the language, you'd probably want to use the two-letter ISO 639-1 code). A file with multiple languages must end with .coll.json (this requirement will probably be lifted in the future).

The basic idea is to write your application in a base language, and use the JSON files to translate text to other languages. For example, lets say you're writing your application in English and translating it to Hebrew, Spanish, and Dutch. You put Spanish and Dutch translations in one file, and since everybody hates Israel, you put Hebrew translations alone. The Spanish and Dutch file can look like this:

        # es_and_nl.coll.json
                "Welcome!": {
                        "es": "Bienvenido!",
                        "nl": "Welkom!"
                "I'm using %1": {
                        "es": "Estoy usando %1",
                        "nl": "Ik gebruik %1"
                "Linux": {} // this line can also be missing entirely

While the Hebrew file can look like this:

        # he.json
                "Welcome!": "ברוכים הבאים!",
                "I'm using %1": "אני משתמש ב%1",
                "Linux": "לינוקס"

When loading these files, Locale::Wolowitz internally merges the two files into one structure:

                "Welcome!" => {
                        "es" => "Bienvenido!",
                        "nl" => "Welkom!",
                        "he" => "ברוכים הבאים!",
                "I'm using %1" => {
                        "es" => "Estoy usando %1",
                        "nl" => "Ik gebruik %1",
                        "he" => "אני משתמש ב%1",
                "Linux" => {
                        "he" => "לינוקס",

Notice the "%1" substrings above. This is a placeholder, just like in other localization paradigms - they are replaced with content you provide, usually dynamic content. In Locale::Wolowitz, placeholders are written with a percent sign, followed by an integer, starting from 1 (e.g. %1, %2, %3). When passing data for the placeholders, make sure you're passing scalars, or printable objects, otherwise you'll encounter errors.

We can also see here that Spanish and Dutch have no translation for "Linux". Since Linux is written "Linux" in these languages, they have no translation. When attempting to translate a string that has no translation to the requested language, or has no reference in the JSON files at all, the string is simply returned as is (but placeholders will still be replaced as expected).

Say you write your application in English (and thus 'en' is your base language). Since Locale::Wolowitz doesn't really know what your base language is, you can translate texts within the same language. This is more useful when you want to give some of your strings an identifier. For example:

        "copyrights": {
                "en": "Copyrights, 2010 Ido Perlmuter",
                "he": "כל הזכויות שמורות, 2010 עידו פרלמוטר"


new( [ $path / $filename, \%options ] )

Creates a new instance of this module. A path to a directory in which JSON localization files exist, or a path to a specific localization file, may be supplied. If you pass a directory, all JSON localization files in it will be loaded and merged as described above. If you pass one file, only that file will be loaded.

Note that Locale::Wolowitz will ignore dotfiles in the provided path (e.g. hidden files, backups files, etc.).

A hash-ref of options can also be provided. The only option currently supported is utf8, which is on by default. If on, all JSON files are assumed to be in UTF-8 character set and will be automatically decoded. Provide a false value if your files are not UTF-8 encoded, for example:

        Locale::Wolowitz->new( '/path/to/files', { utf8 => 0 } );


load_path( $path / $filename )

Receives a path to a directory in which JSON localization files exist, or a path to a specific localization file, and loads (and merges) the localization data from the file(s). If localization data was already loaded previously, the structure will be merged, with the new data taking precedence.

You can call this method and load_structure() as much as you want, the data from each call will be merged with existing data.

load_structure( \%structure, [ $lang ] )

Receives a hash-ref of localization data similar to that in the JSON files and loads it into the object (possibly merging with existing data, if any). If $lang is supplied, a one-to-one structure will be assumed, like so:

                { "hello" => "שלום", "world" => "עולם" },

Or, if $lang is not provided, the structure must be the multiple language structure, like so:

                "hello" => {
                        "he" => "שלום",
                        "fr" => "bonjour"
                "world" => {
                        "he" => "עולם",
                        "fr" => "monde",
                        "it" => "mondo"

You can call this method and load_path() as much as you want, the data from each call will be merged with existing data.

loc( $msg, $lang, [ @args ] )

Returns the string $msg, translated to the requested language (if such a translation exists, otherwise no traslation occurs). Any other parameters passed to the method (@args) are injected to the placeholders in the string (if present).

If an argument is an array ref, it'll be replaced with a recursive call to loc with its elements, with the $lang argument automatically added. In other words, the following two statements are equivalent:

    print $w->loc("I'm using %1", 'he', $w->loc('Linux', 'he'));
    # same result as
    print $w->loc("I'm using %1", 'he', [ 'Linux' ]);

loc_for( $lang )

Returns a function ref that is like loc, but with the $lang curried away.

    use Locale::Wolowitz;

    my $w = Locale::Wolowitz->new( './i18n' );

    my $french_loc  = $w->loc_for('fr');
    my $german_loc  = $w->loc_for('de');

    print $french_loc->('Welcome!'); # equivalent to $w->loc( 'Welcome!', 'fr' )


The following exceptions are thrown by this module:

"You must provide a path to localization directory."

This exception is thrown if you haven't provided the new() subroutine a path to a localization file, or a directory of localization files. Read the documentation for the new() subroutine above.

"Can't open localization directory: %s" and "Can't close localization directory: %s"

This exception is thrown if Locale::Wolowitz failed to open/close the directory of the localization files. This will probably happen due to permission problems. The error message should include the actual reason for the failure.

"Path must be to a directory or a JSON file."

This exception is thrown if you passed a wrong value to the new() subroutine as the path to the localization directory/file. Either the path is wrong and thus does not exist, or the path does exist, but is not a directory and not a file.

"Can't open localization file %s: %s" and "Can't close localization file %s: %s"

This exception is thrown if Locale::Wolowitz fails to open/close a specific localization file. This will usually happen because of permission problems. The error message will include both the name of the file, and the actual reason for the failure.


Locale::Wolowitz requires no configuration files or environment variables.


Locale::Wolowitz depends on the following CPAN modules:

Locale::Wolowitz recommends Cpanel::JSON::XS or JSON::XS for faster parsing of JSON files.


None reported.


No bugs have been reported.

Please report any bugs or feature requests to, or through the web interface at


Ido Perlmuter <>


Copyright 2017 Ido Perlmuter

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.