ANSI Common Lisp 7 Objects 7.7 Dictionary of Objects
||Standard Generic Function
class object slot-name operation &optional new-value
- Method Signatures:
operation &optional new-value
- Arguments and Values:
class - the class of object.
object - an object.
slot-name - a symbol (the name of a would-be slot).
operation - one of the symbols
new-value - an object.
result - an object.
The generic function slot-missing is invoked when an attempt is
made to access a slot in an object whose
metaclass is standard-class
and the slot of the name slot-name
is not a name of a
slot in that class.
The default method signals an error.
The generic function slot-missing is not intended to be called by
programmers. Programmers may write methods for it.
The generic function slot-missing may be called during
evaluation of slot-value, (setf slot-value),
slot-boundp, and slot-makunbound. For each
of these operations the corresponding symbol
for the operation
argument is slot-value, setf, slot-boundp,
and slot-makunbound respectively.
The optional new-value argument to slot-missing is used
when the operation is attempting to set the value of the slot.
If slot-missing returns, its values will be treated as follows:
- Exceptional Situations:
The default method on slot-missing
signals an error of type error.
- See Also:
The set of arguments (including the class of the instance) facilitates
defining methods on the metaclass for slot-missing.
- Allegro CL Implementation Details: