9.6.7 Modifying Instances

Four functions are provided for modifying instances. These functions allow instance slot updates to be performed in blocks without requiring a series of put- messages. Each of these functions returns the symbol TRUE if successful, otherwise the symbol FALSE is returned.

9.6.7.1 Directly Modifying an Instance with Delayed Pattern-Matching

The modify-instance function uses the direct-modify message to change the values of the instance. Object pattern-matching is delayed until all of the slot modifications have been performed.

Syntax

(modify-instance <instance> <slot-override>*)

Example

CLIPS> (clear)
CLIPS>
(defclass A (is-a USER)
  (role concrete)
  (slot foo)
  (slot bar))
CLIPS> (make-instance a of A)
[a]
CLIPS> (watch all)
CLIPS> (modify-instance a (foo 0))
MSG >> direct-modify ED:1 (<Instance-a> <Pointer-0019CD5A>)
HND >> direct-modify primary in class USER.
       ED:1 (<Instance-a> <Pointer-0019CD5A>)
::= local slot foo in instance a <- 0
HND << direct-modify primary in class USER.
       ED:1 (<Instance-a> <Pointer-0019CD5A>)
MSG << direct-modify ED:1 (<Instance-a> <Pointer-0019CD5A>)
TRUE
CLIPS> (unwatch all)
CLIPS>

9.6.7.2 Directly Modifying an Instance with Immediate Pattern-Matching

The active-modify-instance function uses the direct-modify message to change the values of the instance. Object pattern-matching occurs as slot modifications are being performed.

Syntax

(active-modify-instance <instance> <slot-override>*)

9.6.7.3 Modifying an Instance using Messages with Delayed Pattern-Matching

The message-modify-instance function uses the messagemodify message to change the values of the instance. Object pattern-matching is delayed until all of the slot modifications have been performed.

Syntax

(message-modify-instance <instance> <slot-override>*)

Example

CLIPS> (clear)
CLIPS>
(defclass A (is-a USER)
  (role concrete)
  (slot foo)
  (slot bar (create-accessor write)))
CLIPS> (make-instance a of A)
[a]
CLIPS> (watch all)
CLIPS> (message-modify-instance a (bar 4))
MSG >> message-modify ED:1 (<Instance-a> <Pointer-009F04A0>)
HND >> message-modify primary in class USER
       ED:1 (<Instance-a> <Pointer-009F04A0>)
MSG >> put-bar ED:2 (<Instance-a> 4)
HND >> put-bar primary in class A
       ED:2 (<Instance-a> 4)
::= local slot bar in instance a <- 4
HND << put-bar primary in class A
       ED:2 (<Instance-a> 4)
MSG << put-bar ED:2 (<Instance-a> 4)
HND << message-modify primary in class USER
       ED:1 (<Instance-a> <Pointer-009F04A0>)
MSG << message-modify ED:1 (<Instance-a> <Pointer-009F04A0>)
TRUE
CLIPS> (unwatch all)
CLIPS>

9.6.7.4 Modifying an Instance using Messages with Immediate Pattern-Matching

The active-message-modify-instance function uses the message-modify message to change the values of the instance. Object pattern-matching occurs as slot modifications are being performed.

Syntax

(active-message-modify-instance <instance> <slot-override>*)