Common Type System—Mixed Mode Accessibility

Visual C# Tutorials

.NET Framework Tutorials

Common Type System Type Systems Intro § Types and Objects § Type Unification § Reference, Value Types § Accessibility, Visibility § Type Members § Fields § Methods § Locals Overloading Argument Passing Style Pass-by-Value and Pass-by-Reference Output Parameters Managed Pointers Variable Argument Methods Methods, Subclassing Virtuals, Overriding New Slots Exception Handlers Constructors, Instantiation § Default Constructors Value Construction Constructor Chaining Field Initialization Type Initializers Unhandled Exceptions Properties § Indexers Mixed Mode Accessibility Events Operator Overloading Coercion Subclassing, Polymorphism Styles of Inheritance § Implementation Inheritance Interface Inheritance Abstract Classes Interfaces § Method Dispatch Multiple Inheritance Private Interface Inheritance Private Inheritance Accessibility Interface Reimplementation Abstract and Interface? Sealing Types and Methods Runtime Type Checking Namespaces: Organizing Types § Define a Namespace Namespace Resolution Special Types § Delegates § CTS Support Co- and Contravariance Anonymous Delegates Custom Attributes Enumerations § Flags-Style Limitations Helper Methods Generics § Further Reading §

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© 2006 Wiley Publishing Inc.

Mixed Mode Accessibility (Language Feature)

Properties are composed of two bits of code: the getter and setter. As of C# 2.0, you can define these to have separate levels of accessibility. Of course, this isn’t a change to the CTS—you could have previously written this all in IL—but is an improvement for the C# language itself. For example, it’s quite common to provide a public getter and a protected setter. The following syntax enables just that:

class PropertyExample
{
   private int x;
   private int y;
 
   public int X
   {
      get { return x; }
      protected set { x = value; }
   }
 
   public int Y
   {
      get { return y; }
      protected set { y = value; }
   }
}

Notice that the property declaration still has a default accessibility, while the setter has a more restrictive accessibility declared right at the point where you say set.