Function spirit::extension::immutable_cfg

pub fn immutable_cfg<Ext, R, E, N>(extractor: E, name: N) -> impl Extension<Ext> where
    Ext: Extensible,
    E: for<'a> Fn(&'a Ext::Config) -> &R + Send + 'static,
    R: Clone + PartialEq + Send + 'static,
    N: Display + Send + 'static, 

An extension to warn about changes to configuration that can't be updated at runtime.

This is similar to immutable_cfg_init except that there's no callback called at the first load.

Examples

use serde::Deserialize;
use spirit::{Empty, Spirit};
use spirit::prelude::*;
use spirit::extension;

#[derive(Clone, Debug, Default, Deserialize)]
struct Cfg {
    #[serde(default)]
    msg: String,
}

impl Cfg {
    fn msg(&self) -> &String {
        &self.msg
    }
}

fn main() {
    Spirit::<Empty, Cfg>::new()
        // This prints a warning if the message is ever changed during runtime ‒ we can't take
        // it back and change it after it got printed in the body.
        .with(extension::immutable_cfg(Cfg::msg, "message"))
        .run(|spirit| {
            println!("{}", spirit.config().msg);
            Ok(())
        });
}