Getting Started

The simplest way to get started is to install the crate using the default features.

cargo add more-options

Example

The options pattern uses structures to provide strongly typed access to groups of related settings. Options also provide a mechanism to validate configuration data.

Let’s build the ubiquitous Hello World application. The first thing we need to do is define a couple of structures.

use options::Options;
use std::rc::Rc;

pub struct SpeechSettings {
    pub text: String,
    pub language: String,
}

pub struct Person {
    speech: Rc<SpeechSettings>,
}

impl Person {
    pub fn speak(&self) -> &str {
        &self.speech.text
    }
}

You may be wondering why you need Rc. In many practical applications, you’ll have a group of immutable settings which will be used in many places. Rc (or Arc) allows a single instance of settings to be shared throughout the application. You can also use the Ref type alias to switch between them depending on whether the async feature is enabled.

Now that we have some options, we can put it together in a simple application.

use crate::options;

fn main() {
    let options = SpeechSettings {
        text: "Hello world!".into(),
        language: "en".into(),
    };
    let person = Person { speech: options.into() };

    println!("{}", person.speak());
}