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In general, to determine appropriate abstraction, one must make many small decisions about scope (domain analysis), determine what other systems one must cooperate with (legacy analysis), then perform a detailed object-oriented analysis which is expressed within project time and budget constraints as an object-oriented design.
However, the factory only returns a reference (in Java, for instance, by the new operator) or a pointer of an abstract type to the created concrete object. This insulates client code from object creation by having clients request that a factory object create an object of the desired abstract type and return an abstract pointer to the object. [5]
In other words, the object-oriented interface to some service or system. Such an interface is said to be the object model of the represented service or system. For example, the Document Object Model (DOM) is a collection of objects that represent a page in a web browser , used by script programs to examine and dynamically change the page.
In class-based programming, a factory is an abstraction of a constructor of a class, while in prototype-based programming a factory is an abstraction of a prototype object. A constructor is concrete in that it creates objects as instances of one class, and by a specified process (class instantiation), while a factory can create objects by instantiating various classes, or by using other ...
Separate an abstraction (Abstraction) from its implementation (Implementor) by putting them in separate class hierarchies. Implement the Abstraction in terms of (by delegating to) an Implementor object. This enables to configure an Abstraction with an Implementor object at run-time. See also the Unified Modeling Language class and sequence ...
In object oriented programming, objects provide a layer which can be used to separate internal from external code and implement abstraction and encapsulation. External code can only use an object by calling a specific instance method with a certain set of input parameters, reading an instance variable, or writing to an instance variable.
The abstraction principle is mentioned in several books. Some of these, together with the formulation if it is succinct, are listed below. Alfred John Cole, Ronald Morrison (1982) An introduction to programming with S-algol: "[Abstraction] when applied to language design is to define all the semantically meaningful syntactic categories in the language and allow an abstraction over them".
In object-oriented programming, an interface or protocol type [a] is a data type that acts as an abstraction of a class. It describes a set of method signatures, the implementations of which may be provided by multiple classes that are otherwise not necessarily related to each other. [1]