C# in a Nutshell, Second Edition

Chapter 13. Reflection

Many of the services available in .NET and exposed via C# (such as late binding, serialization, remoting, attributes, etc.) depend on the presence of metadata. Your own programs can also take advantage of this metadata, and even extend it with new information. Examining existing types via their metadata is called reflection, and is done using a rich set of types in the System.Reflection namespace. It is also possible to dynamically create new types at runtime via the classes in the System.Reflection.Emit namespace. You can extend the metadata for existing types with custom attributes. For more information, see Chapter 14.

Type Hierarchy

Reflection involves traversing and manipulating an object model that represents an application, including all its compile-time and runtime elements. Consequently, it is important to understand the various logical units of a .NET application and their roles and relationships.

The fundamental units of an application are its types, which contain members and nested types. Types are contained in modules, which are composed into assemblies. All these elements are described with metadata. Metadata is generally produced by the compiler at compile time, although it may also be created on the fly via Reflection.Emit (which is described in the later section “Creating New Types at Runtime”).

At runtime, these elements are all contained within an AppDomain. An AppDomain isn’t described with metadata, yet it plays an important role in reflection ...