8.15 Debugging

Debugging predicates are not available in runtime systems.

unknown(?OldState,?NewState) development

OldState is the current state of the “Action on unknown predicates” flag, and sets the flag to NewState. This flag determines whether or not the system is to catch calls to undefined predicates (see Undefined Predicates), when user:unknown_predicate_handler/3 cannot handle the goal. The possible states of the flag are:

trace

Causes calls to undefined predicates to be reported and the debugger to be entered at the earliest opportunity.

fail

Causes calls to such predicates to fail.

warning

Causes calls to such predicates to display a warning message and then fail.

error

Causes calls to such predicates to raise an exception (the default). See Exception.

debug development

The debugger is switched on in debug mode. See Basic Debug.

trace development

The debugger is switched on in trace mode. See Basic Debug.

zip development

The debugger is switched on in zip mode. See Basic Debug.

nodebug development

notrace

nozip

The debugger is switched off. See Basic Debug.

leash(+Mode) development

Leashing Mode is set to Mode. See Basic Debug.

spy :Spec development

Plain spypoints are placed on all the predicates given by Spec. See Plain Spypoint.

spy(:Spec, :Conditions) development

Spypoints with condition Conditions are placed on all the predicates given by Spec. See Breakpoint Predicates.

nospy :Spec development

All spypoints (plain and conditional) are removed from all the predicates given by Spec. See Plain Spypoint.

nospyall development

Removes all the spypoints (including the generic ones) that have been set.

debugging development

Displays information about the debugger. See Basic Debug.

add_breakpoint(:Conditions, ?BID) development

Creates a breakpoint with Conditions and with identifier BID. See Breakpoint Predicates.

current_breakpoint(:Conditions, ?BID, ?Status, ?Kind, ?Type) development

There is a breakpoint with conditions Conditions, identifier BID, enabledness Status, kind Kind, and type Type. See Breakpoint Predicates.

remove_breakpoints(+BIDs) development

disable_breakpoints(+BIDs)

enable_breakpoints(+BIDs)

Removes, disables or enables the breakpoints specified by BIDs. See Breakpoint Predicates.

execution_state(:Tests) development

Tests are satisfied in the current state of the execution.

execution_state(+FocusConditions, :Tests) development

Tests are satisfied in the state of the execution pointed to by FocusConditions.

debugger_command_hook(+DCommand,?Actions) hook,development

user:debugger_command_hook(+DCommand,?Actions)

Allows the interactive debugger to be extended with user-defined commands. See Debug Commands.

error_exception(+Exception) hook,development

user:error_exception(+Exception)

Tells the debugger to enter trace mode on certain exceptions. See Advanced Debugging.