inline-config

Effortlessly embed config modules and access with any compatible types.

A procedual macro Config is provided to parse sources at compile time, generate corresponding data structures, from which we can access values via the Index trait and the From trait.

Features

• JSON, YAML, TOML formats are supported.
• Both inline literal configs and file inclusions are supported; overwriting is supported.
• Compile-time source validation. Errors are clearly reported for easier debugging.
• Infallible data access. Path existence and type compatibility are both checked at compile time.
• Define custom data structures to access data.
• The feature flag indexmap enables preserving orders of tables. Check this example for details.

Usage

Add inline-config to your dependencies

cargo add inline-config

In your source file, derive a unit struct with Config and attach the config data

use inline_config::Config;

// Declare a config type containing literal sources.
#[derive(Config)]
// While only using literal sources,
// a format needs to be specified.
// Including a file from disk is also possible,
// see `examples/include.rs`.
#[config(format = "toml")]
// When there are multiple sources,
// latter ones overwrite former ones.
#[config(src = r#"
    title = "TOML example"

    [server]
    owner = "Tom"
    timeout = 2000
    ports = [ 8000, 8001, 8002 ]
"#)]
#[config(src = r#"
    [server]
    timeout = 5000
"#)]
struct MyConfig;

Then, access the data inside using the path!() macro

use inline_config::path;

// Use `Index`, `From` traits to access data.
// Different types may be accessible from a field.
let title: &str = MyConfig[path!(title)].into();
assert_eq!("TOML example", title);
let title: String = MyConfig[path!(title)].into();
assert_eq!("TOML example", title);

// A deeper path.
let owner: &str = MyConfig[path!(server.owner)].into();
assert_eq!("Tom", owner);

// Any numerical types.
let timeout: u32 = MyConfig[path!(server.timeout)].into();
assert_eq!(5000, timeout);
let timeout: f32 = MyConfig[path!(server.timeout)].into();

// A homogeneous array can be accessed as `Vec<T>`.
let ports: Vec<u64> = MyConfig[path!(server.ports)].into();
assert_eq!([8000, 8001, 8002].to_vec(), ports);

Check out more examples for more details about usage.