Availability:built-in
prolog_choice_attribute(+ChoicePoint,
+Key, -Value)Extract attributes of a choice point. ChoicePoint is a
reference to a choice point as passed to prolog_trace_interception/4
on the 3rd argument or obtained using prolog_current_choice/1. Key
specifies the requested information:
- parent
- Requests a reference to the first older choice point.
- frame
- Requests a reference to the frame to which the choice point refers.
- type
- Requests the type. Defined values are
clause (the goal has
alternative clauses), foreign (non-deterministic foreign
predicate), jump (clause internal choice point), top
(first dummy choice point), catch (catch/3
to allow for undo),
debug (help the debugger), or none (has been
deleted).
This predicate is used for the graphical debugger to show the choice
point stack.