EventHandlers

EventHandlers are a fundamental concept in many programming paradigms, particularly in event-driven programming. They are essentially functions or methods that are designed to respond to specific events. An event can be anything from a user interaction, such as a mouse click or a key press, to system-level occurrences like a file being loaded or a network connection being established.

When an event occurs, the system triggers a notification. EventHandlers are registered with the system to listen for these specific notifications. Upon receiving a notification for an event they are subscribed to, the EventHandler is executed. This allows programs to react dynamically to external stimuli or internal state changes.

The process typically involves registering an EventHandler with an event source. This registration tells the event source which function to call when a particular event happens. Once registered, the EventHandler sits dormant until the event is dispatched. Upon dispatch, the EventHandler performs its designated task, which could be anything from updating a user interface to processing data or initiating another action.

EventHandlers provide a powerful mechanism for creating responsive and interactive applications. They decouple the code that generates events from the code that handles them, leading to more modular and maintainable software design. This separation of concerns is crucial for building complex systems where different parts of the application need to communicate and react to changes without being tightly coupled. Common examples include handling button clicks in a graphical user interface, responding to network requests, or processing messages in a distributed system.