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Data abstraction enforces a clear separation between the abstract properties of a data type and the concrete details of its implementation. The abstract properties are those that are visible to client code that makes use of the data type—the interface to the data type—while the concrete implementation is kept entirely private, and indeed ...
Data abstraction is a design pattern in which data are visible only to semantically related functions, to prevent misuse. The success of data abstraction leads to frequent incorporation of data hiding as a design principle in object-oriented and pure functional programming.
All object-oriented programming (OOP) systems support encapsulation, [2] [3] but encapsulation is not unique to OOP. Implementations of abstract data types, modules, and libraries also offer encapsulation. The similarity has been explained by programming language theorists in terms of existential types. [4]
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 .
Liskov's notion of a behavioural subtype defines a notion of substitutability for objects; that is, if S is a subtype of T, then objects of type T in a program may be replaced with objects of type S without altering any of the desirable properties of that program (e.g. correctness).
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".
An abstract data type that represents a sequence of values, where the same value may occur more than once. Data order maintenance, implementation of stacks, queues, etc. Stack: A collection that supports a last-in, first-out access pattern. Function calls/recursive calls, undo mechanisms in applications. Queue
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 ...