Macro choice 

choice!() { /* proc-macro */ }

Makes a Choice that the compiler checks.

The instructions come first, in a form that noul! takes. The options come second:

• A type that derives Options. The answer gives a variant.
• An object of names and descriptions. The answer gives the name.
• An array of names. The answer gives the name.
• An array of (name, value) or (name, description, value). The answer gives the value.

Each name is a string literal, so two equal names are a compile error. Each description has a form of the instructions. Each value is a constant expression of any type, and it is not sent. A Choice has 1 to 255 options. For options from data, use Choice::new, Choice::with_descriptions, or Choice::with_values.

Examples

use std::cmp::Ordering;
use system2::{Choice, Options, choice};

#[derive(Debug, Clone, Copy, PartialEq, Options)]
enum Team {
    /// Payments, invoices, and refunds.
    Billing,
    /// Bugs and outages.
    Engineering,
}

const TEAM: Choice<Team> = choice!("Which team must answer the ticket?", Team);
const NEXT: Choice<&str> = choice!("What must the agent do?", {
    "reply": "Reply to the customer.",
    "escalate": "Give the ticket to an engineer.",
});
const LANGUAGE: Choice<&str> = choice!("Which language is the ticket in?", ["en", "de", "fr"]);
const BETTER: Choice<Ordering> = choice!("Which reply is better?", [
    ("first", "The first reply is better.", Ordering::Less),
    ("second", "The second reply is better.", Ordering::Greater),
]);