instance—instance.
Slot-name—a symbol.
The function slot-makunbound
restores a slot
of the name slot-name in an instance to
the unbound state.
If no slot of the name slot-name exists in the
instance, slot-missing
is called as follows:
(slot-missing (class-of instance) instance slot-name 'slot-makunbound)
(Any values returned by slot-missing
in this case are
ignored by slot-makunbound
.)
The specific behavior depends on instance's metaclass.
An error is never signaled if instance has metaclass standard-class
.
An error is always signaled if instance has metaclass built-in-class
.
The consequences are undefined if instance has any other metaclass—an error
might or might not be signaled in this situation. Note in particular that the behavior
for conditions and structures is not specified.
Although no implementation is required to do so,
implementors are strongly encouraged to implement the function slot-makunbound
using the function slot-makunbound-using-class
described in the Metaobject
Protocol.