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ANSI Common Lisp  7 Objects 7.7 Dictionary of Objects
| 7.7.13 slot-unbound |
Standard Generic Function |
- 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.
- 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.
- Allegro CL Implementation Details:
-
None.
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