Struct Driver 

pub struct Driver<T> { /* private fields */ }

Primary driver type that orchestrates parsing and validation.

The driver coordinates all phases of configuration parsing:

1. Parse layers: CLI, environment variables, config files
2. Check special fields: Handle --help, --version, --completions
3. Merge layers: Combine values by priority (CLI > env > file > defaults)
4. Deserialize: Convert merged config into the target type T

Example

use facet::Facet;
use figue::{self as args, builder, Driver};

#[derive(Facet)]
struct Args {
    #[facet(args::positional)]
    file: String,
}

let config = builder::<Args>()
    .unwrap()
    .cli(|cli| cli.args(["input.txt"]))
    .build();

// Create the driver and run parsing
let output = Driver::new(config).run().into_result().unwrap();
assert_eq!(output.value.file, "input.txt");

Implementations

impl<T: Facet<'static>> Driver<T>

pub fn new(config: Config<T>) -> Self

Create a driver from a fully built config.

Use builder() to create the config, then pass it here.

pub fn run(self) -> DriverOutcome<T>

Execute the driver and return an outcome.

The returned DriverOutcome must be handled explicitly:

• Use .unwrap() for automatic exit handling (recommended)
• Use .into_result() if you need manual control