Indirection

Indirection is the use of an intermediate reference or placeholder to access a target value or object rather than accessing the value directly. It creates a separation between the requester and the target, allowing the identity of the target to be changed without altering the requester.

In computing, indirection appears through pointers, references, handles, and indirect addressing. A program may store a memory address in a variable and access the value by dereferencing the address. Levels of indirection, such as pointers to pointers, can increase flexibility but add complexity. High-level languages use references or object handles to decouple names from concrete data, while low-level systems use indirect addressing to widen or relocate memory without changing instructions.

Indirection is also a structural tool in software design. Names or references act as aliases for actual data, enabling abstraction, modularity, and polymorphism. Lazily evaluated or proxied components may be swapped behind a stable interface because callers rely on the indirection rather than direct data access. In file systems and operating systems, symbolic links and file descriptors provide indirection to other files or resources, while databases use views or materialized views as indirections to underlying tables.

Benefits of indirection include decoupling, flexibility, and easier maintenance, since implementations can change without affecting callers. Drawbacks include performance overhead from additional lookup steps, potential for reference errors, and increased cognitive load when reasoning about program behavior. Indirection is a common and powerful concept across computing and information systems, balancing abstraction with practicality.