qr code generator vb.net Building a Hierarchy of Exception Derived Types in Visual Studio .NET

Encode Code39 in Visual Studio .NET Building a Hierarchy of Exception Derived Types

The ExceptionTree sample application (source code shown below) displays all classes that are ultimately derived from System.Exception. However, I wanted to examine types in several assemblies to produce this tree. To accomplish this, the application must explicitly load all the assemblies whose types I want to consider. This is the job of the application s LoadAssemblies method. After loading all the assemblies, the application gets an array of all the AppDomain s assemblies. Then I get an array for all types defined in each assembly. For each type, I check its base type by querying Type s BaseType property. If the Type returned is System.Exception, this type is an exception type. If the Type returned is System.Object, the type isn t an exception type. If the Type returned isn t either of these types, I check the base type s type recursively until I find Exception or Object. The following code is for the ExceptionTree application. The output from this application is shown in 18 (page 408), so I won t display it here.

using using using using System; System.Text; System.Reflection; System.Collections;

class App { static void Main() { // Explicitly load the assemblies that I want to reflect over. LoadAssemblies(); // Initialize the counters and the exception type list. Int32 totalTypes = 0, totalExceptionTypes = 0; ArrayList exceptionTree = new ArrayList(); // Iterate through all assemblies loaded in this AppDomain. foreach (Assembly a in AppDomain.CurrentDomain.GetAssemblies()) { // Iterate through all types defined in this assembly. foreach (Type t in a.GetTypes()) { totalTypes++; // Ignore type if not a public class. if (!t.IsClass || !t.IsPublic) continue; // Build a string of the type s derivation hierarchy. StringBuilder typeHierarchy =

new StringBuilder(t.FullName, 5000); // Assume that the type isn t an Exception derived type. Boolean derivedFromException = false; // See if System.Exception is a base type of this type. Type baseType = t.BaseType; while ((baseType != null) && !derivedFromException) { // Append the base type to the end of the string. typeHierarchy.Append(" " + baseType); derivedFromException = (baseType == typeof(System.Exception)); baseType = baseType.BaseType; } // No more bases and not Exception derived, so try next type. if (!derivedFromException) continue; // I found an Exception derived type. totalExceptionTypes++; // For this Exception derived type, reverse the order // of the types in the hierarchy. String[] h = typeHierarchy.ToString().Split( ); Array.Reverse(h); // Build a new string with the hierarchy in order // from Exception > Exception derived type. // Add the string to the list of Exception types. exceptionTree.Add(String.Join(" ", h, 1, h.Length 1)); } } // Sort the Exception types together in order of their hierarchy. exceptionTree.Sort(); // Display the Exception tree. foreach (String s in exceptionTree) { // For this Exception type, split its base types apart. String[] x = s.Split( ); // Indent based on the number of base types, // and then show the most derived type. Console.WriteLine( new String( , 3 * x.Length) + x[x.Length 1]); } // Show the final status of the types considered. Console.WriteLine("\n > Of {0} types, {1} are " + "derived from System.Exception.", totalTypes, totalExceptionTypes); Console.ReadLine(); } static void LoadAssemblies() { String[] assemblies = { "System, "System.Data, "System.Design, "System.DirectoryServices, "System.Drawing, "System.Drawing.Design,

PublicKeyToken={0}", PublicKeyToken={0}", PublicKeyToken={1}", PublicKeyToken={1}", PublicKeyToken={1}", PublicKeyToken={1}",

"System.EnterpriseServices, "System.Management, "System.Messaging, "System.Runtime.Remoting, "System.Security, "System.ServiceProcess, "System.Web, "System.Web.RegularExpressions, "System.Web.Services, "System.Windows.Forms, "System.Xml, };

PublicKeyToken={1}", PublicKeyToken={1}", PublicKeyToken={1}", PublicKeyToken={0}", PublicKeyToken={1}", PublicKeyToken={1}", PublicKeyToken={1}", PublicKeyToken={1}", PublicKeyToken={1}", PublicKeyToken={0}", PublicKeyToken={0}",

String EcmaPublicKeyToken = "b77a5c561934e089"; String MSPublicKeyToken = "b03f5f7f11d50a3a"; // Get the version of the assembly containing System.Object. // I ll assume the same version for all the other assemblies. Version version = typeof(System.Object).Assembly.GetName().Version; // Explicitly load the assemblies that I want to reflect over. foreach (String a in assemblies) { String AssemblyIdentity = String.Format(a, EcmaPublicKeyToken, MSPublicKeyToken) + ", Culture=neutral, Version=" + version; Assembly.Load(AssemblyIdentity); } } }