A breakpoint represents a function the system calls with the current frame when execution passes a certain code-location. A break point is active or inactive independent of its existence. They also have an extra slot for users to tag the breakpoint with information.
This function creates and returns a breakpoint. When program execution encounters the breakpoint, the system calls hook-function. hook-function takes the current frame for the function in which the program is running and the breakpoint object.
what and kind determine where in a function the system
invokes hook-function. what is either a code-location
or a debug-function. kind is one of
:function-end. Since the starts and
ends of functions may not have code-locations representing them,
designate these places by supplying what as a debug-function
and kind indicating the
:function-end. When what is a debug-function and
:function-end, then hook-function must take two
additional arguments, a list of values returned by the function and
info is information supplied by and used by the user.
function-end-cookie is a function. To implement function-end breakpoints, the system uses starter breakpoints to establish the function-end breakpoint for each invocation of the function. Upon each entry, the system creates a unique cookie to identify the invocation, and when the user supplies a function for this argument, the system invokes it on the cookie. The system later invokes the function-end breakpoint hook on the same cookie. The user may save the cookie when passed to the function-end-cookie function for later comparison in the hook function.
This signals an error if what is an unknown code-location.
Note: Breakpoints in interpreted code or byte-compiled code are not implemented. Function-end breakpoints are not implemented for compiled functions that use the known local return convention (e.g. for block-compiled or self-recursive functions.)
This function causes the system to invoke the breakpoint’s
hook-function until the next call to
delete-breakpoint. The system invokes breakpoint hook
functions in the opposite order that you activate them.
This function stops the system from invoking the breakpoint’s hook-function.
This returns whether breakpoint is currently active.
This function returns the breakpoint’s function the system
calls when execution encounters breakpoint, and it is active.
This function returns breakpoint’s information supplied by the
user. This is
This function returns the breakpoint’s kind specification.
This function returns the breakpoint’s what specification.
This function frees system storage and removes computational overhead associated with breakpoint. After calling this, breakpoint is useless and can never become active again.