defmodule Gettext do
@moduledoc ~S"""
The `Gettext` module provides a
[gettext](https://www.gnu.org/software/gettext/)-based API for working with
internationalized applications.
## Basic Overview
When you use Gettext, you replace hardcoded user-facing text like this:
"Hello world"
with calls like this:
gettext("Hello world")
Here, the string `"Hello world"` serves two purposes:
1. It's displayed by default (if no translation is specified in the current
language). This means that, at the very least, switching from a hardcoded
string to a Gettext call is harmless.
2. It serves as the message ID to which translations will be mapped.
An example translation workflow is as follows.
First, call `mix gettext.extract` to extract `gettext()` calls to `.pot`
([Portable Object Template](https://www.gnu.org/software/gettext/manual/html_node/PO-Files.html))
files, which are the base for all translations. These files are *templates*, which
means they only contain message IDs, and not actual translated strings. POT files have
entries like this:
#: lib/myapp_web/live/hello_live.html.heex:2
#, elixir-autogen, elixir-format
msgid "Hello world"
msgstr ""
Then, call `mix gettext.merge priv/gettext` to update all
locale-specific `.po` (Portable Object) files so that they include this message ID.
Entries in PO files contain translations for their specific locale. For example,
in a PO file for Italian, the entry above would look like this:
#: lib/myapp_web/live/hello_live.html.heex:2
#, elixir-autogen, elixir-format
msgid "Hello world"
msgstr "Ciao mondo"
The English string is the `msgid` which is used to look up the
correct Italian string.
That's handy, because unlike a generic key like `site.greeting` (as some
translations systems use), the message ID tells exactly what needs to be
translated. This is easier to work with for translators, for example.
But it raises a question: what if you change the original English string in the code?
Does that break all translations, requiring manual edits everywhere? Not necessarily.
After you run `mix gettext.extract` again, the next `mix gettext.merge` can
do **fuzzy matching**.
So, if you change `"Hello world"` to `"Hello world!"`, Gettext will see that the new
message ID is similar to an existing `msgid`, and will do two things:
1. It will update the `msgid` in all `.po` files to match the new text.
2. It will mark those entries as "fuzzy"; this hints that a (probably human)
translator should check whether the Italian translation of this string needs
an update.
The resulting change in the `.po` file is this (note the "fuzzy" annotation):
#: lib/myapp_web/live/hello_live.html.heex:2
#, elixir-autogen, elixir-format, fuzzy
msgid "Hello world!"
msgstr "Ciao mondo"
This "fuzzy matching" behavior can be configured or disabled, but its
existence makes updating translations to match changes in the base text easier.
The rest of the documentation will cover the Gettext API in detail.
## Gettext API
To use `Gettext`, a module that calls `use Gettext` (referred to below as a
"backend") has to be defined:
defmodule MyApp.Gettext do
use Gettext, otp_app: :my_app
end
This automatically defines some macros in the `MyApp.Gettext` backend module.
Here are some examples:
import MyApp.Gettext
# Simple message
gettext("Here is the string to translate")
# Plural message
ngettext(
"Here is the string to translate",
"Here are the strings to translate",
3
)
# Domain-based message
dgettext("errors", "Here is the error message to translate")
# Context-based message
pgettext("email", "Email text to translate")
# All of the above
dpngettext(
"errors",
"context",
"Here is the string to translate",
"Here are the strings to translate",
3
)
The arguments for the Gettext macros and their order can be derived from
their names. For `dpgettext/4` the arguments are: `domain`, `context`,
`msgid`, `bindings` (default to `%{}`).
Messages are looked up from `.po` files. In the following sections we will
explore exactly what are those files before we explore the "Gettext API" in
detail.
## Messages
Messages are stored inside PO (Portable Object) files, with a `.po`
extension. For example, this is a snippet from a PO file:
# This is a comment
msgid "Hello world!"
msgstr "Ciao mondo!"
PO files containing messages for an application must be stored in a
directory (by default it's `priv/gettext`) that has the following structure:
gettext directory
└─ locale
└─ LC_MESSAGES
├─ domain_1.po
├─ domain_2.po
└─ domain_3.po
Here, `locale` is the locale of the messages (for example, `en_US`),
`LC_MESSAGES` is a fixed directory, and `domain_i.po` are PO files containing
domain-scoped messages. For more information on domains, check out the
"Domains" section below.
A concrete example of such a directory structure could look like this:
priv/gettext
└─ en_US
| └─ LC_MESSAGES
| ├─ default.po
| └─ errors.po
└─ it
└─ LC_MESSAGES
├─ default.po
└─ errors.po
By default, Gettext expects messages to be stored under the `priv/gettext`
directory of an application. This behaviour can be changed by specifying a
`:priv` option when using `Gettext`:
# Look for messages in my_app/priv/messages instead of
# my_app/priv/gettext
use Gettext, otp_app: :my_app, priv: "priv/messages"
The messages directory specified by the `:priv` option should be a directory
inside `priv/`, otherwise some things won't work as expected.
## Locale
At runtime, all gettext-related functions and macros that do not explicitly
take a locale as an argument read the locale from the backend and fall back
to Gettext's default locale.
`Gettext.put_locale/1` can be used to change the locale of all backends for
the current Elixir process. That's the preferred mechanism for setting the
locale at runtime. `Gettext.put_locale/2` can be used when you want to set the
locale of one specific Gettext backend without affecting other Gettext
backends.
Similarly, `Gettext.get_locale/0` gets the locale for all backends in the
current process. `Gettext.get_locale/1` gets the locale of a specific backend
for the current process. Check their documentation for more information.
Locales are expressed as strings (like `"en"` or `"fr"`); they can be
arbitrary strings as long as they match a directory name. As mentioned above,
the locale is stored **per-process** (in the process dictionary): this means
that the locale must be set in every new process in order to have the right
locale available for that process. Pay attention to this behaviour, since not
setting the locale *will not* result in any errors when `Gettext.get_locale/0`
or `Gettext.get_locale/1` are called; the default locale will be
returned instead.
To decide which locale to use, each gettext-related function in a given
backend follows these steps:
* if there is a backend-specific locale for the given backend for this
process (see `put_locale/2`), use that, otherwise
* if there is a global locale for this process (see `put_locale/1`), use
that, otherwise
* if there is a backend-specific default locale in the configuration for
that backend's `:otp_app` (see the "Default locale" section below), use
that, otherwise
* use the default global Gettext locale (see the "Default locale" section
below)
### Default locale
The global Gettext default locale can be configured through the
`:default_locale` key of the `:gettext` application:
config :gettext, :default_locale, "fr"
By default the global locale is `"en"`. See also `get_locale/0` and
`put_locale/1`.
If for some reason a backend requires a different `:default_locale`
than all other backends, you can set the `:default_locale` inside the
backend configuration, but this approach is generally discouraged as
it makes it hard to track which locale each backend is using:
config :my_app, MyApp.Gettext, default_locale: "fr"
## Gettext API
There are two ways to use Gettext:
* using macros from your own Gettext module, like `MyApp.Gettext`
* using functions from the `Gettext` module
These two approaches are different and each one has its own use case.
### Using macros
Each module that calls `use Gettext` is usually referred to as a "Gettext
backend", as it implements the `Gettext.Backend` behaviour. When a module
calls `use Gettext`, the following macros are automatically
defined inside it:
* `gettext/2`
* `dgettext/3`
* `pgettext/3`
* `dpgettext/4`
* `ngettext/4`
* `dngettext/6`
* `pngettext/6`
* `dpngettext/6`
* all macros above with a `_noop` suffix (and without accepting bindings), for
example `pgettext_noop/2`
Supposing the caller module is `MyApp.Gettext`, the macros mentioned above
behave as follows:
* `gettext(msgid, bindings \\ %{})` -
like `Gettext.gettext(MyApp.Gettext, msgid, bindings)`
* `dgettext(domain, msgid, bindings \\ %{})` -
like `Gettext.dgettext(MyApp.Gettext, domain, msgid, bindings)`
* `pgettext(msgctxt, msgid, bindings \\ %{})` -
like `Gettext.pgettext(MyApp.Gettext, msgctxt, msgid, bindings)`
* `dpgettext(domain, msgctxt, msgid, bindings \\ %{})` -
like `Gettext.dpgettext(MyApp.Gettext, domain, msgctxt, msgid, bindings)`
* `ngettext(msgid, msgid_plural, n, bindings \\ %{})` -
like `Gettext.ngettext(MyApp.Gettext, msgid, msgid_plural, n, bindings)`
* `dngettext(domain, msgid, msgid_plural, n, bindings \\ %{})` -
like `Gettext.dngettext(MyApp.Gettext, domain, msgid, msgid_plural, n, bindings)`
* `pngettext(msgctxt, msgid, msgid_plural, n, bindings \\ %{})` -
like `Gettext.pngettext(MyApp.Gettext, msgctxt, msgid, msgid_plural, n, bindings)`
* `dpngettext(domain, msgctxt, msgid, msgid_plural, n, bindings \\ %{})` -
like `Gettext.dpngettext(MyApp.Gettext, domain, msgctxt, msgid, msgid_plural, n, bindings)`
* `*_noop` family of functions - used to mark messages for extraction
without translating them. See the documentation for these macros in
`Gettext.Backend`
See also the `Gettext.Backend` behaviour for more detailed documentation about
these macros.
Using macros is preferred as Gettext is able to automatically sync the
messages in your code with PO files. This, however, imposes a constraint:
arguments passed to any of these macros have to be strings **at compile
time**. This means that they have to be string literals or something that
expands to a string literal at compile time (for example, a module attribute like
`@my_string "foo"`).
These are all valid uses of the Gettext macros:
Gettext.put_locale(MyApp.Gettext, "it")
MyApp.Gettext.gettext("Hello world")
#=> "Ciao mondo"
@msgid "Hello world"
MyApp.Gettext.gettext(@msgid)
#=> "Ciao mondo"
The `*gettext` macros raise an `ArgumentError` exception if they receive a
`domain`, `msgctxt`, `msgid`, or `msgid_plural` that doesn't expand to a string
*at compile time*:
msgid = "Hello world"
MyApp.Gettext.gettext(msgid)
#=> ** (ArgumentError) msgid must be a string literal
Using compile-time strings isn't always possible. For this reason,
the `Gettext` module provides a set of functions as well.
### Using functions
If compile-time strings cannot be used, the solution is to use the functions
in the `Gettext` module instead of the macros described above. These functions
perfectly mirror the macro API, but they all expect a module name as the first
argument. This module has to be a module which calls `use Gettext`. For example:
defmodule MyApp.Gettext do
use Gettext, otp_app: :my_app
end
Gettext.put_locale(MyApp.Gettext, "pt_BR")
msgid = "Hello world"
Gettext.gettext(MyApp.Gettext, msgid)
#=> "Olá mundo"
While using functions from the `Gettext` module yields the same results as
using macros (with the added benefit of dynamic arguments), all the
compile-time features mentioned in the previous section are lost.
## Domains
The `dgettext` and `dngettext` functions/macros also accept a *domain* as one
of the arguments. The domain of a message is determined by the name of the
PO file that contains that message. For example, the domain of
messages in the `it/LC_MESSAGES/errors.po` file is `"errors"`, so those
messages would need to be retrieved with `dgettext` or `dngettext`:
MyApp.Gettext.dgettext("errors", "Error!")
#=> "Errore!"
When backend `gettext`, `ngettext`, or `pgettext` are used, the backend's
default domain is used (which defaults to "default"). The `Gettext`
functions accepting a backend (`gettext/3`, `ngettext/5`, and `pgettext/4`)
_always_ use a domain of "default".
### Default Domain
Each backend can be configured with a specific `:default_domain`
that replaces `"default"` in `gettext/2`, `pgettext/3`, and `ngettext/4`
for that backend.
defmodule MyApp.Gettext do
use Gettext, otp_app: :my_app, default_domain: "messages"
end
config :my_app, MyApp.Gettext, default_domain: "messages"
## Contexts
The GNU Gettext implementation supports
[*contexts*](https://www.gnu.org/software/gettext/manual/html_node/Contexts.html),
which are a way to contextualize messages. For example, in English, the
word "file" could be used both as a noun as well as a verb. Contexts can be used to
solve similar problems: you could have a `imperative_verbs` context and a
`nouns` context as to avoid ambiguity. The functions that handle contexts
have a `p` in their name (to match the GNU Gettext API), and are `pgettext`,
`dpgettext`, `pngettext`, and `dpngettext`. The "p" stands for "particular".
## Interpolation
All `*gettext` functions and macros provided by Gettext support interpolation.
Interpolation keys can be placed in `msgid`s or `msgid_plural`s with by
enclosing them in `%{` and `}`, like this:
"This is an %{interpolated} string"
Interpolation bindings can be passed as an argument to all of the `*gettext`
functions/macros. For example, given the following PO file for the `"it"`
locale:
msgid "Hello, %{name}!"
msgstr "Ciao, %{name}!"
interpolation can be done like follows:
Gettext.put_locale(MyApp.Gettext, "it")
MyApp.Gettext.gettext("Hello, %{name}!", name: "Meg")
#=> "Ciao, Meg!"
Interpolation keys that are in a string but not in the provided bindings
result in an exception:
MyApp.Gettext.gettext("Hello, %{name}!")
#=> ** (Gettext.MissingBindingsError) ...
Keys that are in the interpolation bindings but that don't occur in the string
are ignored. Interpolations in Gettext are often expanded at compile time,
ensuring a low performance cost when running them at runtime.
## Pluralization
Pluralization in Gettext for Elixir works very similar to how pluralization
works in GNU Gettext. The `*ngettext` functions/macros accept a `msgid`, a
`msgid_plural` and a count of elements; the right message is chosen based
on the **pluralization rule** for the given locale.
For example, given the following snippet of PO file for the `"it"` locale:
msgid "One error"
msgid_plural "%{count} errors"
msgstr[0] "Un errore"
msgstr[1] "%{count} errori"
the `ngettext` macro can be used like this:
Gettext.put_locale(MyApp.Gettext, "it")
MyApp.Gettext.ngettext("One error", "%{count} errors", 3)
#=> "3 errori"
The `%{count}` interpolation key is a special key since it gets replaced by
the number of elements argument passed to `*ngettext`, like if the `count: 3`
key-value pair were in the interpolation bindings. Hence, never pass the
`count` key in the bindings:
# `count: 4` is ignored here
MyApp.Gettext.ngettext("One error", "%{count} errors", 3, count: 4)
#=> "3 errori"
You can specify a "pluralizer" module via the `:plural_forms` option in the
configuration for each Gettext backend.
defmodule MyApp.Gettext do
use Gettext, otp_app: :my_app, plural_forms: MyApp.PluralForms
end
To learn more about pluralization rules, plural forms and what they mean to
Gettext check the documentation for `Gettext.Plural`.
## Missing messages
When a message is missing in the specified locale (both with functions as
well as with macros), the argument is returned:
* in case of calls to `gettext`/`dgettext`/`pgettext`/`dpgettext`, the `msgid` argument is returned
as is;
* in case of calls to `ngettext`/`dngettext`/`pngettext`/`dpngettext`, the `msgid` argument is
returned in case of a singular value and the `msgid_plural` is returned in
case of a plural value (following the English pluralization rule).
For example:
Gettext.put_locale(MyApp.Gettext, "foo")
MyApp.Gettext.gettext("Hey there")
#=> "Hey there"
MyApp.Gettext.ngettext("One error", "%{count} errors", 3)
#=> "3 errors"
### Empty messages
When a `msgstr` is empty (`""`), the message is considered missing and the
behaviour described above for missing message is applied. A plural
message is considered to have an empty `msgstr` if at least one
message in the `msgstr` is empty.
## Compile-time features
As mentioned above, using the Gettext macros (as opposed to functions) allows
Gettext to operate on those messages *at compile-time*. This can be used
to extract messages from the source code into POT (Portable Object Template)
files automatically (instead of having to manually add messages to POT files
when they're added to the source code). The `gettext.extract` does exactly
this: whenever there are new messages in the source code, running
`gettext.extract` syncs the existing POT files with the changed code base.
Read the documentation for `Mix.Tasks.Gettext.Extract` for more information
on the extraction process.
POT files are just *template* files and the messages in them do not
actually contain translated strings. A POT file looks like this:
# The msgstr is empty
msgid "hello, world"
msgstr ""
Whenever a POT file changes, it's likely that developers (or translators) will
want to update the corresponding PO files for each locale. To do that, gettext
provides the `gettext.merge` Mix task. For example, running:
mix gettext.merge priv/gettext --locale pt_BR
will update all the PO files in `priv/gettext/pt_BR/LC_MESSAGES` with the new
version of the POT files in `priv/gettext`. Read more about the merging
process in the documentation for `Mix.Tasks.Gettext.Merge`.
## Configuration
### `:gettext` configuration
The `:gettext` application supports the following configuration options:
* `:default_locale` - a string which specifies the default global Gettext
locale to use for all backends. See the "Locale" section for more
information on backend-specific, global, and default locales.
### Backend configuration
A **Gettext backend** supports some options to be configured. These options
can be configured in two ways: either by passing them to `use Gettext` (hence
at compile time):
defmodule MyApp.Gettext do
use Gettext, options
end
or by using Mix configuration, configuring the key corresponding to the
backend in the configuration for your application:
# For example, in config/config.exs
config :my_app, MyApp.Gettext, options
Note that the `:otp_app` option (an atom representing an OTP application) has
to always be present and has to be passed to `use Gettext` because it's used
to determine the application to read the configuration of (`:my_app` in the
example above); for this reason, `:otp_app` can't be configured via the Mix
configuration. This option is also used to determine the application's
directory where to search messages in.
The following is a comprehensive list of supported options:
* `:priv` - a string representing a directory where messages will be
searched. The directory is relative to the directory of the application
specified by the `:otp_app` option. It is recommended to always have
this directory inside `"priv"`, otherwise some features won't work as expected.
By default it's `"priv/gettext"`.
* `:plural_forms` - a module which will act as a "pluralizer". For more
information, look at the documentation for `Gettext.Plural`.
* `:default_locale` - a string which specifies the default locale to use for
the given backend.
* `:split_module_by` - instead of bundling all locales into a single
module, this option makes Gettext build internal modules per locale,
per domain, or both. This reduces compilation times and beam file sizes
for large projects. For example: `split_module_by: [:locale, :domain]`.
* `:split_module_compilation` - control if compilation of split modules
should happen in `:parallel` (the default) or `:serial`.
* `:allowed_locales` - a list of locales to bundle in the backend.
Defaults to all the locales discovered in the `:priv` directory.
This option can be useful in development to reduce compile-time
by compiling only a subset of all available locales.
* `:interpolation` - the name of a module that implements the
`Gettext.Interpolation` behaviour. Default: `Gettext.Interpolation.Default`
### Mix tasks configuration
You can configure Gettext Mix tasks under the `:gettext` key in the
configuration returned by `project/0` in `mix.exs`:
def project() do
[app: :my_app,
# ...
gettext: [...]]
end
The following is a list of the supported configuration options:
* `:fuzzy_threshold` - the default threshold for the Jaro distance measuring
the similarity of messages. Look at the documentation for the `mix
gettext.merge` task (`Mix.Tasks.Gettext.Merge`) for more information on
fuzzy messages.
* `:excluded_refs_from_purging` - a regex that is matched against message
references. Gettext will preserve all messages in all POT files that
have a matching reference. You can use this pattern to prevent Gettext from
removing messages that you have extracted using another tool.
* `:write_reference_comments` - a boolean that specifies whether reference
comments should be written when outputting PO(T) files. If this is `false`,
reference comments will not be written when extracting messages or merging
messages, and the ones already found in files will be discarded.
* `:write_reference_line_numbers` - a boolean that specifies whether file
reference comments include line numbers when outputting PO(T) files.
Defaults to `true`.
* `:sort_by_msgid` - modifies the sorting behavior. Can be either `nil` (the default),
`:case_sensitive`, or `:case_insensitive`.
By default or if `nil`, the order of existing messages in a POT file is kept and new
messages are appended to the file. If `:sort_by_msgid` is set to `:case_sensitive`,
existing and new messages will be mixed and sorted alphabetically by msgid.
If set to `:case_insensitive`, the same applies but the sorting is case insensitive.
*Note*: this option also supports `true` and `false` for backwards compatibility,
but these values are deprecated as of v0.21.0.
* `:on_obsolete` - controls what happens when obsolete messages are found.
If `:mark_as_obsolete`, messages are kept and marked as obsolete.
If `:delete`, obsolete messages are deleted. Defaults to `:delete`.
* `:store_previous_message_on_fuzzy_match` - a boolean that controls
whether to store the previous message text in case of a fuzzy match.
Defaults to `false`.
"""
alias Gettext.MissingBindingsError
@type locale :: binary
@type backend :: module
@type bindings :: map() | Keyword.t()
@doc false
defmacro __using__(opts) do
# From Elixir v1.13 onwards, use compile_env
env_fun = if function_exported?(Module, :attributes_in, 1), do: :compile_env, else: :get_env
quote do
require Logger
opts = unquote(opts)
otp_app = Keyword.fetch!(opts, :otp_app)
@gettext_opts opts
|> Keyword.merge(Application.unquote(env_fun)(otp_app, __MODULE__, []))
|> Keyword.put_new(:interpolation, Gettext.Interpolation.Default)
@interpolation Keyword.fetch!(@gettext_opts, :interpolation)
@before_compile Gettext.Compiler
def handle_missing_bindings(exception, incomplete) do
_ = Logger.error(Exception.message(exception))
incomplete
end
defoverridable handle_missing_bindings: 2
def handle_missing_translation(_locale, domain, _msgctxt, msgid, bindings) do
Gettext.Compiler.warn_if_domain_contains_slashes(domain)
with {:ok, interpolated} <- @interpolation.runtime_interpolate(msgid, bindings),
do: {:default, interpolated}
end
def handle_missing_plural_translation(
_locale,
domain,
_msgctxt,
msgid,
msgid_plural,
n,
bindings
) do
Gettext.Compiler.warn_if_domain_contains_slashes(domain)
string = if n == 1, do: msgid, else: msgid_plural
bindings = Map.put(bindings, :count, n)
with {:ok, interpolated} <- @interpolation.runtime_interpolate(string, bindings),
do: {:default, interpolated}
end
defoverridable handle_missing_translation: 5, handle_missing_plural_translation: 7
end
end
@doc """
Gets the global Gettext locale for the current process.
This function returns the value of the global Gettext locale for the current
process. This global locale is shared between all Gettext backends; if you
want backend-specific locales, see `get_locale/1` and `put_locale/2`. If the
global Gettext locale is not set, this function returns the default global
locale (configurable in the configuration for the `:gettext` application, see
the module documentation for more information).
## Examples
Gettext.get_locale()
#=> "en"
"""
@spec get_locale() :: locale
def get_locale() do
with nil <- Process.get(Gettext) do
# If this is not set by the user, it's still set in mix.exs (to "en").
Application.fetch_env!(:gettext, :default_locale)
end
end
@doc """
Sets the global Gettext locale for the current process.
The locale is stored in the process dictionary. `locale` must be a string; if
it's not, an `ArgumentError` exception is raised.
The return value is the previous value of the current
process's locale.
## Examples
Gettext.put_locale("pt_BR")
#=> nil
Gettext.get_locale()
#=> "pt_BR"
"""
@spec put_locale(locale) :: locale | nil
def put_locale(locale) when is_binary(locale), do: Process.put(Gettext, locale)
def put_locale(locale),
do: raise(ArgumentError, "put_locale/1 only accepts binary locales, got: #{inspect(locale)}")
@doc """
Gets the locale for the current process and the given backend.
This function returns the value of the locale for the current process and the
given `backend`. If there is no locale for the current process and the given
backend, then either the global Gettext locale (if set), or the default locale
for the given backend, or the global default locale is returned. See the
"Locale" section in the module documentation for more information.
## Examples
Gettext.get_locale(MyApp.Gettext)
#=> "en"
"""
@spec get_locale(backend) :: locale
def get_locale(backend) do
with nil <- Process.get(backend),
nil <- Process.get(Gettext) do
backend.__gettext__(:default_locale)
end
end
@doc """
Sets the locale for the current process and the given `backend`.
The locale is stored in the process dictionary. `locale` must be a string; if
it's not, an `ArgumentError` exception is raised.
The return value is the previous value of the current
process's locale.
## Examples
Gettext.put_locale(MyApp.Gettext, "pt_BR")
#=> nil
Gettext.get_locale(MyApp.Gettext)
#=> "pt_BR"
"""
@spec put_locale(backend, locale) :: locale | nil
def put_locale(backend, locale) when is_binary(locale), do: Process.put(backend, locale)
def put_locale(_backend, locale),
do: raise(ArgumentError, "put_locale/2 only accepts binary locales, got: #{inspect(locale)}")
@doc """
Returns the message of the given string with a given context in the given domain.
The string is translated by the `backend` module.
The translated string is interpolated based on the `bindings` argument. For
more information on how interpolation works, refer to the documentation of the
`Gettext` module.
If the message for the given `msgid` is not found, the `msgid`
(interpolated if necessary) is returned.
## Examples
defmodule MyApp.Gettext do
use Gettext, otp_app: :my_app
end
Gettext.put_locale(MyApp.Gettext, "it")
Gettext.dpgettext(MyApp.Gettext, "errors", "user error", "Invalid")
#=> "Non valido"
Gettext.dgettext(MyApp.Gettext, "errors", "signup form", "%{name} is not a valid name", name: "Meg")
#=> "Meg non è un nome valido"
"""
@spec dpgettext(module, binary, binary | nil, binary, bindings) :: binary
def dpgettext(backend, domain, msgctxt, msgid, bindings \\ %{})
def dpgettext(backend, domain, msgctxt, msgid, bindings) when is_list(bindings) do
dpgettext(backend, domain, msgctxt, msgid, Map.new(bindings))
end
def dpgettext(backend, domain, msgctxt, msgid, bindings)
when is_atom(backend) and is_binary(domain) and is_binary(msgid) and is_map(bindings) do
locale = get_locale(backend)
result = backend.lgettext(locale, domain, msgctxt, msgid, bindings)
handle_backend_result(result, backend, locale, domain, msgctxt, msgid)
end
@doc """
Returns the message of the given string in the given domain.
The string is translated by the `backend` module.
The translated string is interpolated based on the `bindings` argument. For
more information on how interpolation works, refer to the documentation of the
`Gettext` module.
If the message for the given `msgid` is not found, the `msgid`
(interpolated if necessary) is returned.
## Examples
defmodule MyApp.Gettext do
use Gettext, otp_app: :my_app
end
Gettext.put_locale(MyApp.Gettext, "it")
Gettext.dgettext(MyApp.Gettext, "errors", "Invalid")
#=> "Non valido"
Gettext.dgettext(MyApp.Gettext, "errors", "%{name} is not a valid name", name: "Meg")
#=> "Meg non è un nome valido"
Gettext.dgettext(MyApp.Gettext, "alerts", "nonexisting")
#=> "nonexisting"
"""
@spec dgettext(module, binary, binary, bindings) :: binary
def dgettext(backend, domain, msgid, bindings \\ %{}) do
dpgettext(backend, domain, nil, msgid, bindings)
end
@doc """
Returns the message of the given string with the given context
The string is translated by the `backend` module.
The translated string is interpolated based on the `bindings` argument. For
more information on how interpolation works, refer to the documentation of the
`Gettext` module.
If the message for the given `msgid` is not found, the `msgid`
(interpolated if necessary) is returned.
## Examples
defmodule MyApp.Gettext do
use Gettext, otp_app: :my_app
end
Gettext.put_locale(MyApp.Gettext, "it")
Gettext.pgettext(MyApp.Gettext, "user-interface", "Invalid")
#=> "Non valido"
Gettext.pgettext(MyApp.Gettext, "user-interface", "%{name} is not a valid name", name: "Meg")
#=> "Meg non è un nome valido"
Gettext.pgettext(MyApp.Gettext, "alerts-users", "nonexisting")
#=> "nonexisting"
"""
@spec pgettext(module, binary, binary, bindings) :: binary
def pgettext(backend, msgctxt, msgid, bindings \\ %{}) do
dpgettext(backend, "default", msgctxt, msgid, bindings)
end
@doc """
Returns the message of the given string in the `"default"` domain.
Works exactly like:
Gettext.dgettext(backend, "default", msgid, bindings)
"""
@spec gettext(module, binary, bindings) :: binary
def gettext(backend, msgid, bindings \\ %{}) do
dgettext(backend, "default", msgid, bindings)
end
@doc """
Returns the pluralized message of the given string with a given context in the given domain.
The string is translated and pluralized by the `backend` module.
The translated string is interpolated based on the `bindings` argument. For
more information on how interpolation works, refer to the documentation of the
`Gettext` module.
If the message for the given `msgid` and `msgid_plural` is not found, the
`msgid` or `msgid_plural` (based on `n` being singular or plural) is returned
(interpolated if necessary).
## Examples
defmodule MyApp.Gettext do
use Gettext, otp_app: :my_app
end
Gettext.dpngettext(MyApp.Gettext, "errors", "user error", "Error", "%{count} errors", 3)
#=> "3 errori"
Gettext.dpngettext(MyApp.Gettext, "errors", "user error", "Error", "%{count} errors", 1)
#=> "Errore"
"""
@spec dpngettext(module, binary, binary | nil, binary, binary, non_neg_integer, bindings) ::
binary
def dpngettext(backend, domain, msgctxt, msgid, msgid_plural, n, bindings \\ %{})
def dpngettext(backend, domain, msgctxt, msgid, msgid_plural, n, bindings)
when is_list(bindings) do
dpngettext(backend, domain, msgctxt, msgid, msgid_plural, n, Map.new(bindings))
end
def dpngettext(backend, domain, msgctxt, msgid, msgid_plural, n, bindings)
when is_atom(backend) and is_binary(domain) and is_binary(msgid) and is_binary(msgid_plural) and
is_integer(n) and n >= 0 and is_map(bindings) do
locale = get_locale(backend)
result = backend.lngettext(locale, domain, msgctxt, msgid, msgid_plural, n, bindings)
handle_backend_result(result, backend, locale, domain, msgctxt, msgid)
end
@doc """
Returns the pluralized message of the given string in the given domain.
The string is translated and pluralized by the `backend` module.
The translated string is interpolated based on the `bindings` argument. For
more information on how interpolation works, refer to the documentation of the
`Gettext` module.
If the message for the given `msgid` and `msgid_plural` is not found, the
`msgid` or `msgid_plural` (based on `n` being singular or plural) is returned
(interpolated if necessary).
## Examples
defmodule MyApp.Gettext do
use Gettext, otp_app: :my_app
end
Gettext.dngettext(MyApp.Gettext, "errors", "Error", "%{count} errors", 3)
#=> "3 errori"
Gettext.dngettext(MyApp.Gettext, "errors", "Error", "%{count} errors", 1)
#=> "Errore"
"""
@spec dngettext(module, binary, binary, binary, non_neg_integer, bindings) :: binary
def dngettext(backend, domain, msgid, msgid_plural, n, bindings \\ %{}),
do: dpngettext(backend, domain, nil, msgid, msgid_plural, n, bindings)
@doc """
Returns the pluralized message of the given string with a given context
in the `"default"` domain.
Works exactly like:
Gettext.dpngettext(backend, "default", context, msgid, msgid_plural, n, bindings)
"""
@spec pngettext(module, binary, binary, binary, non_neg_integer, bindings) :: binary
def pngettext(backend, msgctxt, msgid, msgid_plural, n, bindings),
do: dpngettext(backend, "default", msgctxt, msgid, msgid_plural, n, bindings)
@doc """
Returns the pluralized message of the given string in the `"default"`
domain.
Works exactly like:
Gettext.dngettext(backend, "default", msgid, msgid_plural, n, bindings)
"""
@spec ngettext(module, binary, binary, non_neg_integer, bindings) :: binary
def ngettext(backend, msgid, msgid_plural, n, bindings \\ %{}) do
dngettext(backend, "default", msgid, msgid_plural, n, bindings)
end
@doc """
Runs `fun` with the global Gettext locale set to `locale`.
This function just sets the global Gettext locale to `locale` before running
`fun` and sets it back to its previous value afterwards. Note that
`put_locale/2` is used to set the locale, which is thus set only for the
current process (keep this in mind if you plan on spawning processes inside
`fun`).
The value returned by this function is the return value of `fun`.
## Examples
Gettext.put_locale("fr")
MyApp.Gettext.gettext("Hello world")
#=> "Bonjour monde"
Gettext.with_locale("it", fn ->
MyApp.Gettext.gettext("Hello world")
end)
#=> "Ciao mondo"
MyApp.Gettext.gettext("Hello world")
#=> "Bonjour monde"
"""
@spec with_locale(locale, (() -> result)) :: result when result: var
def with_locale(locale, fun) when is_binary(locale) and is_function(fun) do
previous_locale = Process.get(Gettext)
Gettext.put_locale(locale)
try do
fun.()
after
if previous_locale do
Gettext.put_locale(previous_locale)
else
Process.delete(Gettext)
end
end
end
@doc """
Runs `fun` with the Gettext locale set to `locale` for the given `backend`.
This function just sets the Gettext locale for `backend` to `locale` before
running `fun` and sets it back to its previous value afterwards. Note that
`put_locale/2` is used to set the locale, which is thus set only for the
current process (keep this in mind if you plan on spawning processes inside
`fun`).
The value returned by this function is the return value of `fun`.
## Examples
Gettext.put_locale(MyApp.Gettext, "fr")
MyApp.Gettext.gettext("Hello world")
#=> "Bonjour monde"
Gettext.with_locale(MyApp.Gettext, "it", fn ->
MyApp.Gettext.gettext("Hello world")
end)
#=> "Ciao mondo"
MyApp.Gettext.gettext("Hello world")
#=> "Bonjour monde"
"""
@spec with_locale(backend(), locale(), (() -> result)) :: result when result: var
def with_locale(backend, locale, fun)
when is_atom(backend) and is_binary(locale) and is_function(fun) do
previous_locale = Process.get(backend)
Gettext.put_locale(backend, locale)
try do
fun.()
after
if previous_locale do
Gettext.put_locale(backend, previous_locale)
else
Process.delete(backend)
end
end
end
@doc """
Returns all the locales for which PO files exist for the given `backend`.
If the messages directory for the given backend doesn't exist, then an
empty list is returned.
## Examples
With the following backend:
defmodule MyApp.Gettext do
use Gettext, otp_app: :my_app
end
and the following messages directory:
my_app/priv/gettext
├─ en
├─ it
└─ pt_BR
then:
Gettext.known_locales(MyApp.Gettext)
#=> ["en", "it", "pt_BR"]
"""
@spec known_locales(backend()) :: [locale()]
def known_locales(backend) when is_atom(backend) do
backend.__gettext__(:known_locales)
end
defp handle_backend_result({:ok, string}, _backend, _locale, _domain, _msgctxt, _msgid) do
string
end
defp handle_backend_result({:default, string}, _backend, _locale, _domain, _msgctxt, _msgid) do
string
end
defp handle_backend_result(
{:missing_bindings, incomplete, missing},
backend,
locale,
domain,
msgctxt,
msgid
) do
exception = %MissingBindingsError{
backend: backend,
locale: locale,
domain: domain,
msgctxt: msgctxt,
msgid: msgid,
missing: missing
}
backend.handle_missing_bindings(exception, incomplete)
end
end
