Encapsulering

Encapsulering, usually called encapsulation in English, is a fundamental principle of software design. It involves bundling data with the procedures that operate on that data and restricting direct access to parts of an object’s internal state. The effect is to expose a well-defined interface while concealing implementation details.

Encapsulation is typically implemented through access controls and modular boundaries. In object-oriented languages, fields may be private or protected and accessed only via public methods, properties, or interfaces. This data hiding supports abstraction by allowing the rest of the program to rely on behavior rather than on the data layout.

Common patterns include keeping data fields private and using getters and setters, or exposing immutable interfaces that prevent modification of internal state. Encapsulation also enables changing the underlying representation without altering external code.

Benefits include reduced coupling, easier maintenance, improved reliability, and better debugging. However, over-encapsulation can introduce boilerplate code and performance overhead, and can lead to excessive accessor usage if not balanced with design clarity.

Encapsulation is closely related to modularity and information hiding, and remains a core concept across programming paradigms, though the exact mechanisms vary by language. The term’s origin lies in object-oriented design, with practical implementations dating to early OO languages such as Simula, Smalltalk, and C++.