Type Reflection

In the .NET universe, reflection is the process of runtime type discovery.

Using reflection services, you are able to programmatically obtain the same metadata information displayed by ildasm.exe using a friendly object model.

For example, through reflection, you can obtain a list of all types contained within a given .dll or .exe assembly, including the methods, fields, properties, and events defined by a given type.

Core items of reflection

Type	Meaning in Life
Assembly	This abstract class contains a number of static methods that allow you to load, investigate, and manipulate an assembly.
AssemblyName	This class allows you to discover numerous details behind an assembly’s identity (version information, culture information, and so forth).
EventInfo	This abstract class holds information for a given event.
FieldInfo	This abstract class holds information for a given field.
MemberInfo	This is the abstract base class that defines common behaviors for the EventInfo, FieldInfo, MethodInfo, and PropertyInfo types.
MethodInfo	This abstract class contains information for a given method.
Module	This abstract class allows you to access a given module within a multifile assembly.
ParameterInfo	This class holds information for a given parameter.
PropertyInfo	This abstract class holds information for a given property.

The System.Type Class

The System.Type class defines a number of members that can be used to examine a type’s metadata, a great number of which return types from the System.Reflection namespace. For example, Type.GetMethods() returns an array of MethodInfo objects.

Type	Meaning in Life
IsAbstract IsArray IsClass IsCOMObject IsEnum IsGenericTypeDefinition IsGenericParameter IsInterface IsPrimitive IsNestedPrivate IsNestedPublic IsSealed IsValueType	These properties (among others) allow you to discover a number of basic traits about the Type you are referring to (e.g., if it is an abstract entity, an array, a nested class, and so forth).
GetConstructors() GetEvents() GetFields() GetInterfaces() GetMembers() GetMethods() GetNestedTypes() GetProperties()	These methods (among others) allow you to obtain an array representing the items (interface, method, property, etc.) you are interested in. Each method returns a related array.
FindMembers()	This method returns a MemberInfo array based on search criteria.
GetType()	This static method returns a Type instance given a string name.
InvokeMember()	This method allows “late binding” for a given item.

GetType() vs typeof(T)

You cannot do is directly create a Type object using the new keyword, as Type is an abstract class.

System.Object defines a method named GetType(), which returns an instance of the Type class that represents the metadata for the current object.

// Obtain type information using a SportsCar instance.
SportsCar sc = new SportsCar();
Type t = sc.GetType(); 

The next way to obtain type information is using the C# typeof operator, like so:

// Get the type using typeof.
Type t = typeof(SportsCar);

Unlike System.Object.GetType(), the typeof operator is compile-time and it does not need to first create an object instance to extract type information.