gistfile1.cs

class Program {
    private delegate void BottlesDelegate(int input);

    static void Main(string[] args) {
        IL();

        Console.WriteLine("Done");
        Console.ReadLine();
    }

    private static void IL() {
        var method = new DynamicMethod("Bottles", typeof (void), new[] {typeof (int)}, typeof (Program).Module);
        var write = typeof(Console).GetMethods(BindingFlags.Public | BindingFlags.Static).Where(x => x.Name == "WriteLine").First(x => x.GetParameters().Length == 1 && x.GetParameters()[0].ParameterType == typeof(string));
        var writeFormatted = typeof (Console).GetMethods(BindingFlags.Public | BindingFlags.Static).Where(x => x.Name == "WriteLine").First(x => x.GetParameters().Length == 2 && x.GetParameters()[0].ParameterType == typeof (string) && x.GetParameters()[1].ParameterType == typeof(object));
        
        var il = method.GetILGenerator();
        var work = il.DefineLabel();

        // Check if we have any bottles left
        il.Emit(OpCodes.Ldarg_0);
        il.Emit(OpCodes.Brtrue, work);
        il.Emit(OpCodes.Ldstr, "No more bottles of beer on the wall, no more bottles of beer.");
        il.Emit(OpCodes.Call, write);
        il.Emit(OpCodes.Ret);

        // Print
        il.MarkLabel(work);
        il.Emit(OpCodes.Ldstr, "{0} bottles of beer on the wall, {0} bottles of beer.");
        il.Emit(OpCodes.Ldarg_0);
        il.Emit(OpCodes.Box, typeof (Int32));
        il.Emit(OpCodes.Call, writeFormatted);

        il.Emit(OpCodes.Ldstr, "Take one down and pass it around. {0} botles of beer.");
        il.Emit(OpCodes.Ldarg_0);
        il.Emit(OpCodes.Ldc_I4, 1);
        il.Emit(OpCodes.Sub);
        il.Emit(OpCodes.Box, typeof (Int32));
        il.Emit(OpCodes.Call, writeFormatted);
        
        // Subtract
        il.Emit(OpCodes.Ldarg_0);
        il.Emit(OpCodes.Ldc_I4, 1);
        il.Emit(OpCodes.Sub);
        il.Emit(OpCodes.Starg, 0);

        // Recurse
        il.Emit(OpCodes.Ldarg_0);
        il.Emit(OpCodes.Call, method);
        il.Emit(OpCodes.Ret);

        var del = method.CreateDelegate(typeof(BottlesDelegate)) as BottlesDelegate;
        del(99);
    }
}