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PHP has hundreds of base functions and thousands more from extensions. Prior to PHP version 5.3.0, functions are not first-class functions and can only be referenced by their name, whereas PHP 5.3.0 introduces closures. [35] User-defined functions can be created at any time and without being prototyped. [35]
Single table inheritance is a way to emulate object-oriented inheritance in a relational database. When mapping from a database table to an object in an object-oriented language , a field in the database identifies what class in the hierarchy the object belongs to. [ 1 ]
The inheritance hierarchy of an object is fixed at instantiation when the object's type is selected and does not change with time. For example, the inheritance graph does not allow a Student object to become an Employee object while retaining the state of its Person superclass.
In software development, the yo-yo problem is an anti-pattern that occurs when a programmer has to read and understand a program whose inheritance graph is so long and complicated that the programmer has to keep flipping between many different class definitions in order to follow the control flow of the program.
Some object-oriented languages, such as Swift, Java, Fortran since its 2003 revision, C#, and Ruby implement single inheritance, although protocols, or interfaces, provide some of the functionality of true multiple inheritance. PHP uses traits classes to inherit specific method implementations. Ruby uses modules to inherit multiple methods.
An object's virtual method table will contain the addresses of the object's dynamically bound methods. Method calls are performed by fetching the method's address from the object's virtual method table. The virtual method table is the same for all objects belonging to the same class, and is therefore typically shared between them.
The concept of the virtual function solves the following problem: In object-oriented programming, when a derived class inherits from a base class, an object of the derived class may be referred to via a pointer or reference of the base class type instead of the derived class type. If there are base class methods overridden by the derived class ...
Based on the type passed to the PersonFactory object, the original concrete object is returned as the interface IPerson. A factory method is just an addition to the PersonFactory class. It creates the object of the class through interfaces but also allows the subclass to decide which class is instantiated.