mod handler
{
    pub type Result<T> = ::std::result::Result<T, HandlerError>;

    pub struct HandlerError;

    pub trait Handler
    {
        fn on_open(&mut self, h: usize) -> Result<()>;
        fn on_message(&mut self, m: bool) -> Result<()>;
    }
}

mod client
{
    use super::handler::{ self, Handler };

    struct Client
    {
        h: usize,
        m: bool,
    }

    impl Handler for Client
    {
        fn on_open(&mut self, h: usize) -> handler::Result<()>
        {
            self.handle_on_open(h)
        }

        fn on_message(&mut self, m: bool) -> handler::Result<()>
        {
            self.handle_on_message(m)
        }
    }

    mod open
    {
        use super::super::handler;
        use super::Client;

        impl Client
        {
            pub fn handle_on_open(&mut self, h: usize) -> handler::Result<()>
            {
                self.h = h;
                Ok(())
            }
        }
    }

    mod message
    {
        use super::super::handler;
        use super::Client;

        impl Client
        {
            pub fn handle_on_message(&mut self, m: bool) -> handler::Result<()>
            {
                self.m = m;
                Ok(())
            }
        }
    }
}