accessor

An accessor, in computer science, is a function, method, or property that provides access to the value of an object's attribute or a data element. Accessors are typically divided into getters, which read or retrieve a value, and setters, which write or assign a value. The term is used across programming languages and libraries to describe the interface that clients use to interact with an object's state, while the underlying representation remains hidden.

In object-oriented programming, accessors support encapsulation by exposing a controlled interface to an object's data. They can enforce invariants, perform validation, or transform values on read or write. Some languages implement accessors through explicit methods (for example, getX and setX in Java or C++) while others provide language features called properties that bundle a getter and a setter into a single attribute-like concept (as in C#, Python, or Kotlin).

Accessors can be simple, returning the value of a private field, or they can be computed properties whose value is derived from other data. They may also implement lazy loading or caching, only computing or retrieving a value when first accessed.

Outside of object-oriented code, the term is used for functions or API endpoints that retrieve data from a structure or database. In functional programming or data libraries, an accessor may be a function that, given a record, returns one of its fields without modifying it.

See also: getter, setter, property, encapsulation, mutator, accessor method.

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