CLIM provides a facility, sometimes referred to as setf* , that allows setf to be used on "places" that name multiple values. For example, output-record-position returns the position of an output record as two values that correspond to the x and y coordinates. In order to change the position of an output record, the programmer would like to invoke (setf output-record-position) . However, setf only takes a single value with which to modify the specified place. The setf* facility provides a "multiple-value" version of setf that allows an expression that returns multiple values to be used to update the specified place.
defgeneric* [Macro]
Arguments: name lambda-list
&body
options
Summary: Defines a setf* generic function named name. The last argument in lambda-list is intended to be class specialized, just as normal setf generic functions are. options are as for defgeneric .
defmethod* [Macro]
Arguments: name (method-qualifier* specialized-lambda-list
&body
body)
Summary: Defines a setf* method for the generic function name . The last argument in specialized-lambda-list is intended to be class specialized, just as normal setf methods are. (method-qualifier)* and body are as for defgeneric . For example, output-record-position and its setf* method for a class called sample-output-record might be defined as follows:
(defgeneric output-record-position (record)
(defgeneric* (setf output-record-position) (x y record))
(defmethod output-record-position ((record sample-output-record))
(defmethod* (setf output-record-position)
(nx ny (record sample-output-record))
The position of such an output record could then be changed as follows:
(setf (output-record-position record) (values nx ny))
(setf (output-record-position record1)
(output-record-position record2))