Plug-ins in C# 2.0: Generics Enabled Extension Library

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using ExtensionManager;
using Common;


namespace HostApplication
{
	public partial class frmHost : Form, IHost
	{
		public frmHost()
		{
			InitializeComponent();
		}

		//Our manager object
		ExtensionManager<IExtension, IHost> manager = new ExtensionManager<IExtension, IHost>();		

		private void frmHost_Load(object sender, EventArgs e)
		{
			//Listen to the events
			manager.AssemblyFailedLoading += new ExtensionManager<IExtension, IHost>.AssemblyFailedLoadingEventHandler(manager_AssemblyFailedLoading);
			manager.AssemblyLoaded += new ExtensionManager<IExtension, IHost>.AssemblyLoadedEventHandler(manager_AssemblyLoaded);
			manager.AssemblyLoading += new ExtensionManager<IExtension, IHost>.AssemblyLoadingEventHandler(manager_AssemblyLoading);

			//Loads .cs, .vb, .js, and .dll extensions
			manager.LoadDefaultFileExtensions();

			//We need to add our library with the interfaces to the list
			manager.SourceFileReferencedAssemblies.Add("Common.dll");

			//Lookin in the AppPath\Extensions\ folder
			manager.LoadExtensions(Application.StartupPath.TrimEnd("\\".ToCharArray()) + "\\Extensions\\");

			//Loop through all the extensions
			foreach (Extension<IExtension> extOn in manager.Extensions)
			{
				//It needs to know we're the host!
				extOn.Instance.Host = this;

				//Create a new listitem
				ListViewItem lvi = new ListViewItem(extOn.Instance.Title);
				lvi.Tag = extOn.Instance; //Store our instance in the tag for easy retrieval later

				//Add to the list
				this.listExtensions.Items.Add(lvi);
			}
		}

		void manager_AssemblyLoading(object sender, AssemblyLoadingEventArgs e)
		{
			//Simply update status
			statusLabel.Text = "Loading: " + e.Filename;
		}

		void manager_AssemblyLoaded(object sender, AssemblyLoadedEventArgs e)
		{
			statusLabel.Text = "Loaded: " + e.Filename;
		}

		void manager_AssemblyFailedLoading(object sender, AssemblyFailedLoadingEventArgs e)
		{
			//Build an error message with specific compiler errors
			StringBuilder msg = new StringBuilder();
			msg.AppendLine("Failed Loading Extension: " + e.Filename + " of Type: " + e.ExtensionType.ToString());
			msg.AppendLine("Error Message: ");
			msg.AppendLine(e.ErrorMessage);
			msg.AppendLine(" ");
			msg.AppendLine("Compiler Errors: ");

			foreach (System.CodeDom.Compiler.CompilerError errorOn in e.SourceFileCompilerErrors)
				msg.AppendLine("  #" + errorOn.ErrorNumber.ToString() + " on Line: " + errorOn.Line.ToString() + " at Column: " + errorOn.Column.ToString() + " - " + errorOn.ErrorText);

			//Show the user
			MessageBox.Show(this, msg.ToString(), "Compilation Error", MessageBoxButtons.OK);
		}

		#region IHost Members
		public void HostStatus(string statusMessage)
		{
			//Change the status label
			this.statusLabel.Text = statusMessage;
		}
		#endregion

		private void listExtensions_DoubleClick(object sender, EventArgs e)
		{
			//Make sure an item is selected
			if (this.listExtensions.SelectedItems.Count > 0)
			{
				//Get the instance
				IExtension extInstance = (IExtension)this.listExtensions.SelectedItems[0].Tag;

				//If we have an instance, call process!
				if (extInstance != null)
					extInstance.Process();
			}
		}
	}
}