C# how to use read method in assembly type

Question

I am writing a Data Acquisition app that uses a wrapper class around HW drivers. My goal is for external users should be able to write their own wrappers for their hardware. It seems assemblies is the way to store these driver wrappers, to be loaded by the app. So I have started with a very simple test code based on a Microsoft example: Loading DLLs at runtime in C# It works when writing to the an assembly method. I added a read method and that does not work. See code:

namespace DLL
{
    using System;

    public class Class1
    {
        public void Output(string s)
        {
            Console.WriteLine(s);
        }
        public string DriverName()      // My added method
        {
            return "Test";
        }
    }
}

And here is the main:

namespace ConsoleApplication1
{
    using System;
    using System.Reflection;

    // See: https://stackoverflow.com/questions/18362368/loading-dlls-at-runtime-in-c-sharp
    
    public class Program
    {
        public static void Main(string[] args)
        {
            var DLL = Assembly.LoadFile(@"...\Documents\VS\Tests\DLL Test\DLL\bin\Debug\netstandard2.0\DLL.dll");
            foreach (Type type in DLL.GetExportedTypes())
            
                dynamic c = Activator.CreateInstance(type);
                c.Output("Hello");                    // Works
                Console.WriteLine(c.DriverName());    // Doesn't work
            }
            Console.ReadLine();
        }
    }
}

It gives a compile-time error: Microsoft.CSharp.RuntimeBinder.RuntimeBinderException: ''DLL.Class1' does not contain a definition for 'DriverName''

How come this only works one way but not the other? Is there a simple fix?

"does not work" is not very descriptive. Can you elaborate please? — Guru Stron, Jan 24 '21 at 14:15
Please describe "does not work": any compile time errors, runtime errors, other behaviour that helps us pinpoint the issue? — Hans Keﬆing, Jan 24 '21 at 14:16
Tip: instead of using a dynamic, require that external class to implement an interface that you supply. That way the compiler knows it can expect certain methods and properties — Hans Keﬆing, Jan 24 '21 at 14:18
If you put c.DriverName() in a variable and debug it, how does it look like? — Maytham Fahmi, Jan 24 '21 at 14:18
I checked also. It works just fine. was not able to reproduce it. — Nantharupan, Jan 24 '21 at 14:34
I moved the code to a new solution and now it works! Thanks! — bes, Jan 24 '21 at 14:51

score 1 · Answer 1 · answered Jan 24 '21 at 14:36

try putting in parentheses

namespace ConsoleApplication1
{
    using System;
    using System.Reflection;

    // See: https://stackoverflow.com/questions/18362368/loading-dlls-at-runtime-in-c-sharp
    
    public class Program
    {
        public static void Main(string[] args)
        {
            var DLL = Assembly.LoadFile(@"...\Documents\VS\Tests\DLL Test\DLL\bin\Debug\netstandard2.0\DLL.dll");
            foreach (Type type in DLL.GetExportedTypes())
            {
                dynamic c = Activator.CreateInstance(type);
                c.Output("Hello");                    // Works
                Console.WriteLine(c.DriverName());    // Doesn't work
            }
            Console.ReadLine();
        }
    }
}

C# how to use read method in assembly type

1 Answers1