accessors

Accessors in programming are methods or language features that provide controlled access to the fields of an object or data structure. They are typically divided into getters, which read a value, and setters, which write a value. The primary purpose of accessors is to preserve encapsulation by exposing a public interface while keeping the underlying representation private or hidden from direct use.

In many languages, accessors are implemented as explicit methods, such as a getX() method to retrieve a field or a setX(value) method to assign it. Some languages offer more concise or automatic forms. For example, languages like C# provide properties with get and set blocks; Java uses explicit getX/setX methods; Python can implement accessors via the @property decorator to define a managed attribute. Other languages offer built-in property syntax that makes accessors feel like simple field access while still routing through logic behind the scenes.

Accessors enable several design benefits, including validation or transformation of data, lazy loading or caching, and change notification when a value is updated. They also allow the internal representation to change without affecting external code that relies on the public interface. However, overusing accessors can introduce boilerplate or obscure performance concerns; when a setter merely forwards to a field, some developers argue that it adds little value and can hinder the design of immutable objects or more meaningful abstractions.

Related concepts include read-only properties (getters without setters), computed or derived properties (values calculated on access), and the distinction between accessors (read/write) and mutators (write operations that may have side effects).

---