CLHS: Standard Generic Function SLOT-UNBOUND

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Standard Generic Function SLOT-UNBOUND

Syntax:

slot-unbound class instance slot-name => result*

Method Signatures:

slot-unbound (class t) instance slot-name

Arguments and Values:

class---the class of the instance.

instance---the instance in which an attempt was made to read the unbound slot.

slot-name---the name of the unbound slot.

result---an object.

Description:

The generic function slot-unbound is called when an unbound slot is read in an instance whose metaclass is standard-class. The default method signals an error of type unbound-slot. The name slot of the unbound-slot condition is initialized to the name of the offending variable, and the instance slot of the unbound-slot condition is initialized to the offending instance.

The generic function slot-unbound is not intended to be called by programmers. Programmers may write methods for it. The function slot-unbound is called only indirectly by slot-value.

If slot-unbound returns, only the primary value will be used by the caller, and all other values will be ignored.

Examples: None.

Affected By: None.

Exceptional Situations:

The default method on slot-unbound signals an error of type unbound-slot.

See Also:

slot-makunbound

Notes:

An unbound slot may occur if no `:initform` form was specified for the slot and the slot value has not been set, or if slot-makunbound has been called on the slot.

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

- SLOT-MISSING-VALUES:SPECIFY
- UNDEFINED-VARIABLES-AND-FUNCTIONS:COMPROMISE

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