gettext

go-gettext

GNU gettext utilities for Go, forked from https://github.com/leonelquinteros/gotext

WARNING

This repository has been moved to github.com/lestrrat-go/gettext. This repository exists so that libraries pointing to this URL will keep functioning, but this repository will NOT be updated in the future. Please use the new import path.

Features

Features Specific To This Fork

• Properly reports errors
• gettext.LocaleSet wrapper to handle multiple languages dynamically

Features From Fork Source

• Implements GNU gettext support in native Go.
• Complete support for PO files including:
  • Support for multiline strings and headers.
  • Support for variables inside translation strings using Go's fmt syntax.
  • Support for pluralization rules.
  • Support for message contexts.
• Thread-safe: This package is safe for concurrent use across multiple goroutines.
• Woorks with UTF-8 encoding as it's the default for Go language.
• Language codes are automatically simplified from the form en_UK to en if the first isn't available.
• Ready to use inside Go templates.

License

MIT license

Installation

go get github.com/lestrrat/go-gettext

• There are no requirements or dependencies to use this package.
• No need to install GNU gettext utilities (unless specific needs of CLI tools).
• No need for environment variables. Some naming conventions are applied but not needed.

Locales directories structure

The package will assume a directories structure starting with a base path that will be provided to the package configuration or to object constructors depending on the use, but either will use the same convention to lookup inside the base path.

Inside the base directory where will be the language directories named using the language and country 2-letter codes (en_US, es_AR, ...). All package functions can lookup after the simplified version for each language in case the full code isn't present but the more general language code exists. So if the language set is en_UK, but there is no directory named after that code and there is a directory named en, all package functions will be able to resolve this generalization and provide translations for the more general library.

The language codes are assumed to be ISO 639-1 codes (2-letter codes). That said, most functions will work with any coding standard as long the directory name matches the language code set on the configuration.

Then, there can be a LC_MESSAGES containing all PO files or the PO files themselves.
A library directory structure can look like:

/path/to/locales
/path/to/locales/en_US
/path/to/locales/en_US/LC_MESSAGES
/path/to/locales/en_US/LC_MESSAGES/default.po
/path/to/locales/en_US/LC_MESSAGES/extras.po
/path/to/locales/en_UK
/path/to/locales/en_UK/LC_MESSAGES
/path/to/locales/en_UK/LC_MESSAGES/default.po
/path/to/locales/en_UK/LC_MESSAGES/extras.po
/path/to/locales/en_AU
/path/to/locales/en_AU/LC_MESSAGES
/path/to/locales/en_AU/LC_MESSAGES/default.po
/path/to/locales/en_AU/LC_MESSAGES/extras.po
/path/to/locales/es
/path/to/locales/es/default.po
/path/to/locales/es/extras.po
/path/to/locales/es_ES
/path/to/locales/es_ES/default.po
/path/to/locales/es_ES/extras.po
/path/to/locales/fr
/path/to/locales/fr/default.po
/path/to/locales/fr/extras.po

And so on...

About translation function names

The standard GNU gettext defines helper functions that maps to the gettext() function and it's widely adopted by most implementations.

The basic translation function is usually _() in the form:

_("Translate this")

In Go, this can't be implemented by a reusable package as the function name has to start with a capital letter in order to be exported.

Each implementation of this package can declare this helper functions inside their own packages if this function naming are desired/needed:

package main

import "github.com/lestrrat/go-gettext"

func _(str string, vars ...interface{}) string {
    return gettext.Get(str, vars...)
}

This is valid and can be used within a package.

In normal conditions the Go compiler will optimize the calls to _() by replacing its content in place of the function call to reduce the function calling overhead. This is a normal Go compiler behavior.

Usage examples

Using dynamic variables on translations

All translation strings support dynamic variables to be inserted without translate. Use the fmt.Printf syntax (from Go's "fmt" package) to specify how to print the non-translated variable inside the translation string.

import "github.com/lestrrat/go-gettext"

func main() {
    l := gettext.NewLocale("en_US", 
        WithSource(NewFileSystemSource("/path/to/locales/root/dir")))
    l.AddDomain("domain-name")
    
    // Set variables
    name := "John"
    
    // Translate text with variables
    println(gettext.Get("Hi, my name is %s", name))
}

Using Locale object

import "github.com/lestrrat/go-gettext"

func main() {
    // Create Locale with library path and language code
    l := gettext.NewLocale("es_UY", 
        WithSource(NewFileSystemSource("/path/to/locales/root/dir")))
    
    // Load domain '/path/to/locales/root/dir/es_UY/default.po'
    l.AddDomain("default")
    
    // Translate text from default domain
    println(l.Get("Translate this"))
    
    // Load different domain
    l.AddDomain("translations")
    
    // Translate text from domain
    println(l.GetD("translations", "Translate this"))
}

You may pass the locale object to text/template (or the like) to localize your templates. If you set the Locale object as "Loc" in the template, then the template code would look like:

{{ .Loc.Get "Translate this" }}

Use a different source for .po files

When you want to embed everything in a go binary, including the .po files, you can use the WithSource option.

import "github.com/lestrrat/go-gettext"

func main() {
    // Create Locale with library path and language code, and use
    // the `Asset` function that is generated by asset packers, e.g
    // github.com/lestrrat/go-packasset or github.com/tmthrgd/go-bindata
    l := gettext.NewLocale("es_UY", WithSource(SourceFunc(Asset)))

    // Load domain '/path/to/locales/root/dir/es_UY/default.po'
    l.AddDomain("default")

    // Translate text from default domain
    println(l.Get("Translate this"))

    // Load different domain
    l.AddDomain("translations")

    // Translate text from domain
    println(l.GetD("translations", "Translate this"))
}

Using the Po object to handle .po files and PO-formatted strings

For when you need to work with PO files and strings, you can directly use the Po object to parse it and access the translations in there in the same way.

import "github.com/lestrrat/go-gettext"

func main() {
    // Set PO content
    str := `
msgid "Translate this"
msgstr "Translated text"

msgid "Another string"
msgstr ""

msgid "One with var: %s"
msgstr "This one sets the var: %s"
`
    po, err := NewParser().ParseString(str)
    if err != nil {
        ...
    }
    
    println(po.Get("Translate this"))
}

Use plural forms of translations

PO format supports defining one or more plural forms for the same translation. Relying on the PO file headers, a Plural-Forms formula can be set on the translation file as defined in (https://www.gnu.org/savannah-checkouts/gnu/gettext/manual/html_node/Plural-forms.html)

Plural formulas are parsed and evaluated using Anko

import "github.com/lestrrat/go-gettext"

func main() {
    // Set PO content
    str := `
msgid ""
msgstr ""

# Header below
"Plural-Forms: nplurals=2; plural=(n != 1);\n"

msgid "Translate this"
msgstr "Translated text"

msgid "Another string"
msgstr ""

msgid "One with var: %s"
msgid_plural "Several with vars: %s"
msgstr[0] "This one is the singular: %s"
msgstr[1] "This one is the plural: %s"
`
    po, err := NewParser().ParseString(str)
    if err != nil {
        ...
    }

    println(po.GetN("One with var: %s", "Several with vars: %s", 54, v))
    // "This one is the plural: Variable"
}

ACKNOWLEDGEMENTS

• Based on https://github.com/leonelquinteros/gotext