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  ANSI Common Lisp   7 Objects   7.7 Dictionary of Objects

7.7.11 slot-makunbound Function

slot-makunbound instance slot-name    instance

Arguments and Values:
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.

Exceptional Situations:
If no slot of the name slot-name exists in the instance, slot-missing is called as follows:

(slot-missing (class-of instance)

(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.

See Also:
slot-boundp, slot-missing

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.

Allegro CL Implementation Details:

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