C# 0 The Complete Reference

protected

 in conjunction with 

internal

 to produce the 

protected internal

access modifier pair. The 

protected internal

 access level can be given only to class members. 

A member declared with 

protected internal

 access is accessible within its own assembly or 

to derived types.

Here is an example that uses 

internal

:

// Use internal.

using System;

class InternalTest {

  internal int x;

}

class InternalDemo {

  static void Main() {

    InternalTest ob = new InternalTest();

    ob.x = 10; // can access -- in same file

    Console.WriteLine("Here is ob.x: " + ob.x);

  }

}

Inside

InternalTest

, the field 

x

 is declared 

internal

. This means that it is accessible within 

the program, as its use in 

InternalDemo

 shows, but unavailable outside the program.

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17

Runtime Type ID, Reflection, 

and Attributes

T

his chapter discusses three interrelated and powerful features: runtime type 

identification, reflection, and attributes. 

Runtime type ID

 is the mechanism that lets 

you identify a type during the execution of a program. 

Reflection

 is the feature that 

enables you to obtain information about a type. Using this information, you can construct 

and use objects at runtime. This feature is very powerful because it lets a program add 

functionality dynamically, during execution. An 

attribute

 describes a characteristic of some 

element of a C# program. For example, you can specify attributes for classes, methods, and 

fields, among others. Attributes can be interrogated at runtime, and the attribute information 

obtained. Attributes use both runtime type identification and reflection.