using System;

public delegate void LogHandler(string s);

public class Process {
    public void Run(LogHandler lh) {
        lh("Start process");
        //...
        lh("Stop process");
    }
}

public class Tracer {
    public void Trace(string s) {
        System.Console.WriteLine("Tracer: {0}", s);
    }
}

public class Test {
    public static void Log(string s) {
        System.Console.WriteLine("static Log: {0}", s);
    }

    public static int Main(string[] args) {
        Process p = new Process();
        Tracer t = new Tracer();
        LogHandler lh = null;
        // lh = (LogHandler) Delegate.Combine(
        //     lh,
        //     new LogHandler(Log)
        // );
        lh += new LogHandler(Log);

        // lh = (LogHandler) Delegate.Combine(
        //     lh,
        //     new LogHandler(t.Trace)
        // );
        lh += new LogHandler(t.Trace);
        p.Run(lh);
        return 0;
    }
}