Object<<Goal
Calls a goal within the context of the specified object. Goal is called with the execution context (sender, this, and self) set to Object. Goal may need to be written within brackets to avoid parsing errors due to operator clashes. This control construct is mainly used for debugging and for writing object unit tests. This control construct can only be used for objects compiled with the compiler option context_switching_calls
set to allow
. Set this compiler option to deny
to disable this control construct.
+object_identifier<<+callable
instantiation_error
type_error(object_identifier, Object)
type_error(callable, Goal)
existence_error(procedure, Goal)
existence_error(object, Object)
permission_error(access, predicate, Goal)
test(member) :- list << member(1, [1]).