C# Events Dll Interface

Question

I have dlls sum and interface

public interface IPlugin
{
    string Name {get; }
    string GetDescription();

    double GetLastResult { get; }
    double Execute(double value1, double value2);

    event EventHandler OnExecute;

    void ExceptionTest(string input);
}

public class Sum : IPlugin
{      
    public string Name
    {
        get { return "Sum"; }
    }

    public event EventHandler OnExecute;
}

How to make event like I take name of dll,event say that name was taken?

DLL loaded like this:

private PluginInterface.IPlugin LoadAssembly(string assemblyPath)
{
    string assembly = Path.GetFullPath(assemblyPath);
    Assembly ptrAssembly = Assembly.LoadFile(assembly);

    foreach (Type item in ptrAssembly.GetTypes())
    {
        if (!item.IsClass) continue;
        if (item.GetInterfaces().Contains(typeof(PluginInterface.IPlugin)))
        {
            return (PluginInterface.IPlugin)Activator.CreateInstance(item);
        }
    }
    throw new Exception("Invalid DLL, Interface not found!");
}

IPlugin currPlugin;
currPlugin = LoadAssembly("pathtodll");
MessageBox.Show(currPlugin.Name);

I tried to made event like this:

currPlugin.OnExecute += currPlugin_OnExecute; //subscribe to dll
void currPlugin_OnExecute(object sender, EventArgs e)
{
    MessageBox.Show("Event OnExecute triggered from DLL " + ((PluginInterface.IPlugin)sender).Name);
}

But i don't know what to do next Please,help...

Answer 1

You need raise the event OnExecute inside double Execute(double value1, double value2) implementation.

This example is just for test.

internal class Program
{
    private static void Main(string[] args)
    {
        //load the .exe assembly using reflection(just for testing)
        var currPlugin = LoadAssembly(Assembly.GetEntryAssembly().Location);
        Console.WriteLine(currPlugin.Name);
        currPlugin.OnExecute += currPlugin_OnExecute;
        currPlugin.Execute(10d, 20d);
    }

    private static void currPlugin_OnExecute(object sender, EventArgs e)
    {
        var plugin = (IPlugin) sender;

        Console.WriteLine("Event OnExecute triggered from DLL '{0}'", plugin.GetType().Assembly.FullName);
        Console.WriteLine("[{0}] Event OnExecute -> {1}", plugin.Name, plugin.GetLastResult);
    }

    private static IPlugin LoadAssembly(string assemblyPath)
    {
        string assembly = Path.GetFullPath(assemblyPath);
        Assembly ptrAssembly = Assembly.LoadFile(assembly);

        foreach (Type item in ptrAssembly.GetTypes())
        {
            if (!item.IsClass) continue;
            if (item.GetInterfaces().Contains(typeof (IPlugin)))
            {
                return (IPlugin) Activator.CreateInstance(item);
            }
        }
        throw new Exception("Invalid DLL, Interface not found!");
    }
}

public interface IPlugin
{
    string Name { get; }
    string GetDescription();

    double GetLastResult { get; }
    double Execute(double value1, double value2);

    event EventHandler OnExecute;

    void ExceptionTest(string input);
}

public class Sum : IPlugin
{
    private double _lastResult = double.NaN;

    public string Name
    {
        get { return "Sum"; }
    }

    public string GetDescription()
    {
        return "Plugin description";
    }

    public double GetLastResult
    {
        get { return _lastResult; }
    }

    public double Execute(double value1, double value2)
    {
        _lastResult = value1 + value2;
        OnExecuteInvoke();
        return _lastResult;
    }

    public event EventHandler OnExecute;

    protected virtual void OnExecuteInvoke()
    {
        var handler = OnExecute;
        if (handler != null)
            handler(this, EventArgs.Empty);
    }

    public void ExceptionTest(string input)
    {
        throw new Exception(input);
    }
}

Answer 2

public interface IPlugin { void Execute(); event EventHandler OnExecute; } public class Sum : IPlugin { public void Execute() { if (this.OnExecute != null) this.OnExecute(this, new EventArgs()); } public event EventHandler OnExecute; } ////////// use Sum sum = new Sum(); Console.WriteLine("Before subscribe"); sum.Execute(); sum.OnExecute += new EventHandler(sum_OnExecute); Console.WriteLine("After subscribe"); sum.Execute();