EventArgsEmpty

EventArgs.Empty is a static, read-only instance of the EventArgs class used in the .NET framework to represent an event that carries no data. It serves as a singleton to avoid creating multiple identical EventArgs objects for events that do not convey additional information beyond the event trigger.

The primary purpose of EventArgs.Empty is to optimize event invocation. For events that use the standard EventHandler delegate (which has the signature void Handler(object sender, EventArgs e)), developers can pass EventArgs.Empty in place of creating a new EventArgs object each time the event is raised. This reduces memory allocations and helps improve performance in scenarios with frequent event firing.

Usage norms include raising events with EventArgs.Empty when there is no data to convey. For example, when notifying subscribers that a generic action has occurred, the event can be invoked with the sender and EventArgs.Empty rather than null or a newly constructed EventArgs. It is common to see patterns like invoking the event using a null-conditional operator or a local copy of the delegate, then passing EventArgs.Empty as the second argument.

EventArgs.Empty is a predefined singleton, and as such, it is a shared instance. Because it is a single, immutable object, comparisons against EventArgs.Empty are not typically meaningful; its use is primarily about signaling the absence of data and avoiding extra allocations.

Notes: EventHandler<TEventArgs> delegates use typed EventArgs and typically require specific event data; EventArgs.Empty is not suitable for those handlers unless the type is exactly EventArgs. The field is part of the standard library and is widely used in example code and framework components.