Programming .NET Components, 2nd Edition

System.Type

The abstract class Type, defined in the System namespace, is an abstraction of a .NET CLR type. Every .NET type, be it a .NET-provided type (from value types such as integers and enums to classes and interfaces) or a developer-defined type, has a corresponding unique Type value.

Tip

The ability to uniquely identify a type by means of a Type object is analogous to the COM idea of identifying the type of a component by means of its unique CLSID.

The canonical base class of any .NET type is System.Object. Object (or just object in C#) has built-in support for retrieving the Type associated with any object by calling its GetType() method:

    public class Object
    {
       public Type GetType();
       //Other methods
    }

Having GetType() present in object allows you to call it on any .NET object:

    public class MyClass
    {...}

    int number = 0;
    MyClass obj = new MyClass();

    Type type1 = number.GetType();
    Type type2 = obj.GetType();

Different instances of the same type must return the same Type value:

    int number1 = 1;
    int number2 = 2;

    Type type1 = number1.GetType();
    Type type2 = number2.GetType();

    Debug.Assert(type1 
            == 
            type2);

The typeof operator allows you to retrieve the Type associated with a type directly, without instantiating an object of that type:

    Type type1 = typeof(int);
    Type type2 = typeof(MyClass);

Type is your gateway to obtaining the metadata associated with a given type. To start, Type.ToString() returns the type’s name:

 Type type = typeof(MyClass); string name = type.ToString(); Debug.Assert(name ...