foo.rs

extern crate term;
use term::Terminal;

struct ShellConfig {
    color: int,
    verbose: int,
    tty: bool,
}
enum AdequateTerminal<T> {
    Color(Box<Terminal<T>>)
}
struct Shell<T> {
    terminal: AdequateTerminal<T>,
    config: ShellConfig,
}
impl <T: Writer + Send> Shell<T> {
    fn create(out: T, config: ShellConfig) -> Option<Shell<T>> {
        let term: Option<term::TerminfoTerminal<T>> = Terminal::new(out);
        term.map(|t: term::TerminfoTerminal<T>| Shell { terminal: Color(box t), config: config })
    }
}