actions.rs

macro_rules! actions({ 
    $( $action: expr => $function: expr ), + } => {{
        let mut store = ::std::collections::HashMap::new();
        $(store.insert($action as &str, $function as Box<Fn(&str)>);) + store
    }};
);

fn main() {
    let actions = actions!{
        "foo" => Box::new(|arg: &str| println!("foo {}", arg)),
        "bar" => Box::new(|arg: &str| println!("bar {}", arg))
    };
    
    match actions.get("foo") {
        Some(action) => action("stuff"),
        None => return,  
    }
    
    match actions.get("bar") {
        Some(action) => action("other stuff"),
        None => return,  
    }
}