callbacki

Callbacki are a programming construct in which a function or code fragment is passed as an argument to another function and is intended to be invoked later, usually in response to an event or the completion of an asynchronous task. The plural form callbacki is used in several languages to refer to multiple such procedures.

The main purpose of callbacki is to enable decoupling and extensibility: the callee controls when to run the code, while the caller supplies the specific behavior. This pattern supports flexible APIs and modular design by allowing behavior to be customized without modifying the callee.

Common use cases include asynchronous I/O, event handling, and library APIs that invoke back when work finishes or when a user action occurs. They are also used to implement callbacks in GUI toolkits, network requests, timers, and streaming data processing.

Language examples vary. In JavaScript, callbacks are central to many APIs for network requests and timers. In Python, callbacks appear in GUI toolkits and in asyncio protocols. In C, callbacks are implemented via function pointers passed to other functions. In Java, functional interfaces and lambdas can serve as callbacks, especially in event-driven code.

Challenges and patterns include the risk of callback nesting, sometimes referred to as callback hell, and error handling conventions such as error-first callbacks in some ecosystems. Alternatives and aids include promises, async/await, futures, and reactive programming approaches to improve readability and control flow. Best practices emphasize clear naming, keeping callbacks small and non-blocking, and thorough documentation of expected inputs, outputs, and error handling.