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Perl uses the list of classes to inherit from as an ordered list. The compiler uses the first method it finds by depth-first searching of the superclass list or using the C3 linearization of the class hierarchy. Various extensions provide alternative class composition schemes. The order of inheritance affects the class semantics.
C# can be considered as similar to Java, in terms of its language features and basic syntax: Java has JVM, C# has .Net Framework; Java has bytecode, C# has MSIL; Java has no pointers (real memory) support, C# is the same. Regarding the final keyword, C# has two related keywords: The equivalent keyword for methods and classes is sealed
A snippet of Java code with keywords highlighted in blue and bold font. In the Java programming language, a keyword is any one of 68 reserved words [1] that have a predefined meaning in the language. Because of this, programmers cannot use keywords in some contexts, such as names for variables, methods, classes, or as any other identifier. [2]
For example, a parent class, A, can have two subclasses B and C. Both B and C's parent class is A, but B and C are two separate subclasses. Hybrid inheritance Hybrid inheritance is when a mix of two or more of the above types of inheritance occurs. An example of this is when a class A has a subclass B which has two subclasses, C and D.
Not all languages support multiple inheritance. For example, Java allows a class to implement multiple interfaces, but only inherit from one class. [22] If multiple inheritance is allowed, the hierarchy is a directed acyclic graph (or DAG for short), otherwise it is a tree. The hierarchy has classes as nodes and inheritance relationships as links.
There will be sub-classes each of which is derived from one of the super-classes. The sub-classes are mutually linked via fields, and each sub-class may override the methods inherited from the super-class. New methods and fields are usually declared in one sub-class. [1] The following diagram shows the typical structure of multiple inheritance:
On the other hand, inheritance can be statically type-checked, while delegation generally cannot without generics (although a restricted version of delegation can be statically typesafe [7]). Delegation can be termed "run-time inheritance for specific objects." Here is a pseudocode example in a C#/Java like language:
The C++ examples in this section demonstrate the principle of using composition and interfaces to achieve code reuse and polymorphism. Due to the C++ language not having a dedicated keyword to declare interfaces, the following C++ example uses inheritance from a pure abstract base class.