BreakpointEvent

BreakpointEvent is a term used in debugging to describe a signal emitted by a debugger or debugging protocol when execution reaches a breakpoint or when the state of a breakpoint changes. It is used to inform the debugging client that the program has paused or that a breakpoint-related condition has been met, enabling the user interface to present the current execution context and debugging controls.

The data associated with a BreakpointEvent typically includes identifiers for the breakpoint (such as an id or index), the location of the breakpoint (source file and line number, and optionally column), the thread or process affected, and the reason for the event (for example a breakpoint hit, breakpoint enabled/disabled, or a conditional evaluation result). Many implementations also provide a hit count, a short description, a conditional expression result, and a compact stack trace to aid inspection.

Behavioral aspects: when a breakpoint is hit, execution may pause according to the debugger’s suspend policy. The event prompts the client to display the current call stack, local variables, and source context, and to offer debugging actions such as resume, step over, step into, or evaluate expressions. Breakpoint state changes can trigger updates to the user interface without qualifying a new run of code.

In practice, BreakpointEvent appears across debugging environments and protocol specifications as part of the communication contract between the debugger engine and front-end clients. It supports consistent handling of breakpoints for diverse languages and platforms.