replace-standard-object Function

Summary

Replaces the values in a CLOS object's slots by the values of slots from another object.

Package

clos

Signature

replace-standard-object target source => target

Arguments

target⇩, source⇩

A standard-object, but not a funcallable-standard-object.

Values

target

A standard-object, but not a funcallable-standard-object.

Description

The function replace-standard-object replaces the values in the slots of the CLOS object target by the values of slots from the CLOS object source.

Only slots with allocation type :instance are copied from source to target.

source and target must be of type standard-object, excluding funcallable-standard-object and its subclasses, in particular they cannot be of type generic-function. Moreover both must be of the same class, that is:

(eq (class-of target) (class-of source)) => t

The replacement is shallow, that is only the actual values are copied, as if by:

(dolist (slot instance-slots)
  (setf (slot-value target slot)
        (slot-value source slot)))

assuming no definition that affects what slot-value and (setf slot-value) do. However, replace-standard-object bypasses the slot-value mechanism and is much faster.

replace-standard-object should be used on instances of user-defined classes which do not inherit from system-defined classes (other than standard-object). It should never be used on instances of system-defined classes and their subclasses.

The return value is eq to the argument target.

See also

copy-standard-object