This print for content only-size & color not accurate 7" X 9-1/4" / casebound / malloy

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Source Code

The MyTypeViewer project can be found under the Chapter 16 subdirectory.

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T Y P E   R E F L E C T I O N, L AT E   B I N D I N G, A N D  AT T R I B U T E - B A S E D   P R O G R A M M I N G

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8849CH16.qxd  10/9/07  4:27 PM  Page 535

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Dynamically Loading Assemblies

In the previous chapter, you learned all about how the CLR consults the assembly manifest when

probing for an externally referenced assembly. However, there will be many times when you need

to load assemblies on the fly programmatically, even if there is no record of said assembly in the

manifest. Formally speaking, the act of loading external assemblies on demand is known as a

dynamic load.

System.Reflection defines a class named Assembly. Using this type, you are able to dynamically

load an assembly as well as discover properties about the assembly itself. Using the Assembly type,

you are able to dynamically load private or shared assemblies, as well as load an assembly located

at an arbitrary location. In essence, the Assembly class provides methods (Load() and LoadFrom() in

particular) that allow you to programmatically supply the same sort of information found in a

client-side *.config file.

To illustrate dynamic loading, create a brand-new Console Application named External

AssemblyReflector. Your task is to construct a Main() method that prompts for the friendly name of

an assembly to load dynamically. You will pass the Assembly reference into a helper method named

DisplayTypes(), which will simply print the names of each class, interface, structure, enumeration,

and delegate it contains. The code is refreshingly simple:

using System;

using System.Reflection;

using System.IO;  // For FileNotFoundException definition.

namespace ExternalAssemblyReflector

{

class Program

{

static void DisplayTypesInAsm(Assembly asm)

{

Console.WriteLine("\n***** Types in Assembly *****");

Console.WriteLine("->{0}", asm.FullName);

Type[] types = asm.GetTypes();

foreach (Type t in types)

Console.WriteLine("Type: {0}", t);

Console.WriteLine("");

}

static void Main(string[] args)

{

Console.WriteLine("***** External Assembly Viewer *****");

string asmName = "";

bool userIsDone = false;

Assembly asm = null;

do

{

Console.WriteLine("\nEnter an assembly to evaluate");

Console.Write("or enter Q to quit: ");