Common Type System—Methods and Subclassing

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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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Methods and Subclassing

We discuss subtyping and polymorphism in much greater detail later on in this chapter. But assuming that you are at least somewhat familiar with standard OO idioms, we will discuss virtual methods, overriding, and newslots here. All you need to understand for this discussion is that a type may subclass another type, forming a special relationship between them. The subclass inherits its base type’s nonprivate members, including methods. The topic here is controlling how those methods get inherited.