# i18n-embed-fl [](https://crates.io/crates/i18n-embed-fl) [](https://docs.rs/i18n-embed-fl/) [](https://github.com/kellpossible/cargo-i18n/blob/master/i18n-embed-fl/LICENSE.txt) [](https://github.com/kellpossible/cargo-i18n/actions?query=workflow%3ARust)
This crate provides a macro to perform compile time checks when using the [i18n-embed](https://crates.io/crates/i18n-embed) crate and the [fluent](https://www.projectfluent.org/) localization system.
See [docs](https://docs.rs/i18n-embed-fl/), and [i18n-embed](https://crates.io/crates/i18n-embed) for more information.
**[Changelog](https://github.com/kellpossible/cargo-i18n/blob/master/i18n-embed-fl/CHANGELOG.md)**
## Example
Set up a minimal `i18n.toml` in your crate root to use with `cargo-i18n` (see [cargo i18n](../README.md#configuration) for more information on the configuration file format):
```toml
# (Required) The language identifier of the language used in the
# source code for gettext system, and the primary fallback language
# (for which all strings must be present) when using the fluent
# system.
fallback_language = "en-GB"
# Use the fluent localization system.
[fluent]
# (Required) The path to the assets directory.
# The paths inside the assets directory should be structured like so:
# `assets_dir/{language}/{domain}.ftl`
assets_dir = "i18n"
```
Create a fluent localization file for the `en-GB` language in `i18n/en-GB/{domain}.ftl`, where `domain` is the rust path of your crate (`_` instead of `-`):
```fluent
hello-arg = Hello {$name}!
```
Simple set up of the `FluentLanguageLoader`, and obtaining a message formatted with an argument:
```rust
use i18n_embed::{
fluent::{fluent_language_loader, FluentLanguageLoader},
LanguageLoader,
};
use i18n_embed_fl::fl;
use rust_embed::RustEmbed;
#[derive(RustEmbed)]
#[folder = "i18n/"]
struct Localizations;
let loader: FluentLanguageLoader = fluent_language_loader!();
loader
.load_languages(&Localizations, &[loader.fallback_language()])
.unwrap();
assert_eq!(
"Hello \u{2068}Bob 23\u{2069}!",
// Compile time check for message id, and the `name` argument,
// to ensure it matches what is specified in the `fallback_language`'s
// fluent resource file.
fl!(loader, "hello-arg", name = format!("Bob {}", 23))
)
```
## Convenience Macro
You will notice that this macro requires `loader` to be specified in every call. For you project you may have access to a statically defined loader, and you can create a convenience macro wrapper so this doesn't need to be imported and specified every time.
```rust
macro_rules! fl {
($message_id:literal) => {{
i18n_embed_fl::fl!($crate::YOUR_STATIC_LOADER, $message_id)
}};
($message_id:literal, $($args:expr),*) => {{
i18n_embed_fl::fl!($crate::YOUR_STATIC_LOADER, $message_id, $($args), *)
}};
}
```
This can now be invoked like so: `fl!("message-id")`, `fl!("message-id", args)` and `fl!("message-id", arg = "value")`.