This document discusses .NET reflection, which allows examining types at runtime to access metadata and dynamically invoke methods, properties, and fields without knowing the specific types at compile time. It describes using the System.Reflection and System.Type classes to reflect on types and members. Dynamic loading of external assemblies and late binding techniques are also covered, along with attributed programming and some predefined attributes in .NET. Building custom attributes by inheriting from the System.Attribute class is demonstrated.

1. Reflection
Code Review 8/16/12

2. Where is this info?
METADATA!

3. Type Reflection
In the .NET universe, reflection is the process of runtime type
discovery
System.Reflection namespace
Assembly, AssemblyName, EventInfo, FieldInfo, MethodInfo,
ParameterInfo and PropertyInfo
System.Type class
GetConstructors(), GetEvents(), GetFields(), GetInterfaces(),
GetMembers(), GetMethods(), GetProperties(), InvokeMember()

4. Reflect the type info
Obtain a type reference using System.Type.GetType()
Type t = Type.GetType (typeName);
Reflecting on methods
MethodInfo[] mi = t.GetMethods();
Reflecting on Fields and properties
FieldInfo[] fi = t.GetFields();
PropertyInfo[] pi = t.GetProperties();

5. Dynamic Loading
Dynamic load
loading external assemblies on
demand
Can use Assembly.Load() or
Assembly.LoadFrom()

6. Late binding
Late binding is a technique in which you are
able to create an instance of a given type and
invoke its members at runtime without having
compile-time knowledge of its existence
Assembly a = Assembly.Load(“CarLibrary”);Type miniVan = a.GetType
(“CarLibrary.MiniVan”);
object obj = Activator.CreateInstance(miniVan);
MethodInfo mi = miniVan.GetMethod(“TurboBoost”);
mi.Invoke(obj, null);

7. Attributed programming
Using attributes, programmers can
embed additional metadata into an
assembly
.NET attributes are class types that
extend the abstract System.Attribute
base class

8. Attribute Consumers
.Net Compiler
.Net base libraries (such as Serialize())
Custom Code

9. Predefined attributes
[CLSCompliant]
[DllImport]
[Obsolete]
[Serializable]
[NonSerialized]
[WebMethod]

10. Building Custom Attributes
public sealed class VehicleDescriptionAttribute: System.Attribute
{
private string msgData;
public VehicleDescriptionAttribute (string description) {
msgData = description;}
}