CLHS: Function SLOT-MAKUNBOUND

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Function SLOT-MAKUNBOUND

Syntax:

slot-makunbound instance slot-name => instance

Arguments and Values:

instance -- instance.

Slot-name---a symbol.

Description:

The function slot-makunbound restores a slot of the name slot-name in an instance to the unbound state.

Examples: None.

Affected By: None.

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)
                  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.

See Also:

slot-boundp, slot-missing

Notes:

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.

The following X3J13 cleanup issues, not part of the specification, apply to this section:

- SLOT-VALUE-METACLASSES:LESS-MINIMAL
- SLOT-MISSING-VALUES:SPECIFY

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