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Return to Abstraction (computer science), Data Abstraction, Liskov Substitution Principle, Object-Oriented Programming

Abstraction in computer programming is a way to reduce complexity and allow efficient design and implementation in complex software systems. It hides the technical complexity of systems behind simpler APIs.

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• Helps the user to avoid writing low level code.
• Avoids code duplication and increases code reusability.
• Can change internal implementation of class independently without affecting the user.
• Helps to increase security of an application or program as only important details are provided to the user.

Snippet from Wikipedia: Abstraction (computer science)

In software engineering and computer science, abstraction is the process of generalizing concrete details, such as attributes, away from the study of objects and systems to focus attention on details of greater importance. Abstraction is a fundamental concept in computer science and software engineering, especially within the object-oriented programming paradigm. Examples of this include:

• the usage of abstract data types to separate usage from working representations of data within programs;
• the concept of functions or subroutines which represent a specific way of implementing control flow;
• the process of reorganizing common behavior from groups of non-abstract classes into abstract classes using inheritance and sub-classes, as seen in object-oriented programming languages.

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Snippet from Wikipedia: Liskov substitution principle

The Liskov substitution principle (LSP) is a particular definition of a subtyping relation, called strong behavioral subtyping, that was initially introduced by Barbara Liskov in a 1987 conference keynote address titled Data abstraction and hierarchy. It is based on the concept of "substitutability" – a principle in object-oriented programming stating that an object (such as a class) may be replaced by a sub-object (such as a class that extends the first class) without breaking the program. It is a semantic rather than merely syntactic relation, because it intends to guarantee semantic interoperability of types in a hierarchy, object types in particular. Barbara Liskov and Jeannette Wing described the principle succinctly in a 1994 paper as follows:

Subtype Requirement: Let ${\displaystyle \phi (x)}$ be a property provable about objects ${\displaystyle x}$ of type T. Then ${\displaystyle \phi (y)}$ should be true for objects ${\displaystyle y}$ of type S where S is a subtype of T.

Symbolically:

${\displaystyle S\leq T\to (\forall x{:}T.\phi (x)\to \forall y{:}S.\phi (y))}$

That is, if S subtypes T, what holds for T-objects holds for S-objects. In the same paper, Liskov and Wing detailed their notion of behavioral subtyping in an extension of Hoare logic, which bears a certain resemblance to Bertrand Meyer's design by contract in that it considers the interaction of subtyping with preconditions, postconditions and invariants.

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Data Abstraction

Return to C++ abstraction, Golang abstraction

Abstraction is a process or result of generalization, removal of properties, or distancing of ideas from objects.

abstraction - “The principle of ignoring those aspects of a subject that are not relevant to the current purpose in order to concentrate solely on those that are. The application of this principle is essential in the development and understanding of all forms of computer system. See data abstraction, procedural abstraction.” (Fair Use ODCS)

Disambiguation:

Abstraction may also refer to:

• Abstraction (computer science), a process of hiding details of implementation in programs and data
  • Abstract class
  • Abstraction layer, an application of abstraction in computing
    • Hardware abstraction, an abstraction layer on top of hardware

• Abstraction (linguistics), use of terms for concepts removed from the objects to which they were originally attached

• Abstraction (mathematics), a process of removing the dependence of a mathematical concept on real-world objects
  • Lambda abstraction, a definition of an anonymous function that produces a valid term in lambda calculus

• Abstract (disambiguation)
• Abstract art, a movement in 20th-century Western art. Abstraction (art), art unconcerned with the literal depiction of things from the visible world

Return to Glossaries, C++ glossary, Programming glossary

“Abstraction is the act of specifying a general interface hiding implementation details. Classes, abstract classes, and templates are the primary abstraction mechanisms in C plus plus C++. See also: encapsulation.”

Fair Use Source: http://www.stroustrup.com/glossary.html