How to load Assembly at runtime and create class instance?

I have a assembly. In this assembly I have a class and interface. I need to load this assembly at runtime and want to create an object of the class and also want to use the interface.

Assembly MyDALL = Assembly.Load("DALL"); // DALL is name of my dll
Type MyLoadClass = MyDALL.GetType("DALL.LoadClass"); // LoadClass is my class
object obj = Activator.CreateInstance(MyLoadClass);

This is my code. How could it be improved?


If your assembly is in GAC or bin use the assembly name at the end of type name instead of Assembly.Load().

object obj = Activator.CreateInstance(Type.GetType("DALL.LoadClass, DALL", true));

You should Use Dynamic Method with for Improving. its faster than reflection..

Here is a sample code for creating Object using Dynamic Method..

public class ObjectCreateMethod
{
    delegate object MethodInvoker();
    MethodInvoker methodHandler = null;

    public ObjectCreateMethod(Type type)
    {
        CreateMethod(type.GetConstructor(Type.EmptyTypes));
    }

    public ObjectCreateMethod(ConstructorInfo target)
    {
        CreateMethod(target);
    }

    void CreateMethod(ConstructorInfo target)
    {
        DynamicMethod dynamic = new DynamicMethod(string.Empty,
                    typeof(object),
                    new Type[0],
                    target.DeclaringType);
        ILGenerator il = dynamic.GetILGenerator();
        il.DeclareLocal(target.DeclaringType);
        il.Emit(OpCodes.Newobj, target);
        il.Emit(OpCodes.Stloc_0);
        il.Emit(OpCodes.Ldloc_0);
        il.Emit(OpCodes.Ret);

        methodHandler = (MethodInvoker)dynamic.CreateDelegate(typeof(MethodInvoker));
    }

    public object CreateInstance()
    {
        return methodHandler();
    }
}

//Use Above class for Object Creation.
ObjectCreateMethod inv = new ObjectCreateMethod(type); //Specify Type
Object obj= inv.CreateInstance();

This method takes only 1/10th time needed by Activator.

Check out http://www.ozcandegirmenci.com/post/2008/02/Create-object-instances-Faster-than-Reflection.aspx


Check out http://www.youtube.com/watch?v=x-KK7bmo1AM To modify his code to load multiple assemblies use

static Assembly CurrentDomain_AssemblyResolve(object sender, ResolveEventArgs args)
        {
            string assemblyName = args.Name.Split(',').First();
            using (var stream = Assembly.GetExecutingAssembly().GetManifestResourceStream("YourNamespace." + assemblyName + ".dll"))
            {
                byte[] assemblyData = new byte[stream.Length];
                stream.Read(assemblyData, 0, assemblyData.Length);
                return Assembly.Load(assemblyData);
            }
        }
In your main method put
AppDomain.CurrentDomain.AssemblyResolve += CurrentDomain_AssemblyResolve;
Be sure to add your assemblies to your project and change the build action property to "Embedded Resource".