load and unload of assemblies dynamically

Hello @Dieter Oeschay

Thanks for your question.

To load and unload assemblies dynamically, I recommend using AssemblyLoadContext. You can refer to these following steps:

Load

• Step 1: Create a custom load context Add to your WPD project:

using System.Reflection;
using System.Runtime.Loader;

public class PluginLoadContext : AssemblyLoadContext
{
    private AssemblyDependencyResolver _resolver;

    public PluginLoadContext(string pluginPath)
        : base(isCollectible: true)
    {
        _resolver = new AssemblyDependencyResolver(pluginPath);
    }

    protected override Assembly Load(AssemblyName assemblyName)
    {
        string assemblyPath = _resolver.ResolveAssemblyToPath(assemblyName);
        if (assemblyPath != null)
        {
            return LoadFromAssemblyPath(assemblyPath);
        }
        return null;
    }
}

• Step 2: Create your plugin

Create a new Class Library project:

using System;

namespace MySimplePlugin
{
    public class Calculator
    {
        public string Name => "Calculator v2.0";

        public void Execute()
        {
            Console.WriteLine("Calculating 2 + 2 = 4");
        }

        public int Add(int a, int b)
        {
            return a + b;
        }
    }
}

• Step 3: Load the plugin

string dllPath = @"C:\Plugins\MySimplePlugin.dll";
PluginLoadContext loadContext = new PluginLoadContext(dllPath);


Assembly assembly = loadContext.LoadFromAssemblyPath(dllPath);

Type pluginType = assembly.GetType("MySimplePlugin.Calculator");
object pluginInstance = Activator.CreateInstance(pluginType);

var nameProperty = pluginType.GetProperty("Name");
string name = (string)nameProperty.GetValue(pluginInstance);

var executeMethod = pluginType.GetMethod("Execute");
executeMethod.Invoke(pluginInstance, null);

Unload

• Step 1: Clear all references to the plugin.

pluginInstance = null;
assembly = null;

• Step 2: Unload the context

loadContext.Unload();

• Step 3: Force garbage collection.

GC.Collect();
GC.WaitForPendingFinalizers();
GC.Collect();

I hope this addresses your question. If this response was helpful, please consider following the guidance to provide feedback.