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tot_constraint(7/26/90) tot_constraint(7/26/90)

NAME

tot_constraint - represent tactical constraint between two TOT objects

DESCRIPTION

The tot_constraint object represents a tactical constraint between two TOT objects, its predecessor, and its successor. A message is defined for the predecessor and the successor. It must be a query message that returns a float. The values returned by the predecessor and successor are subtracted and compared with a delta value stored in the constraint object. If the constraint is violated, the constraint object is drawn, and an alert box is displayed.

SUPERCLASS

object

INSTANCE VARIABLES

pred name of the predecessor object.

succ name of the successor object.

pred_msg query message to send to the predecessor. Must return a float.

succ_msg query message to send to the successor. Must return a float.

delta value which the successor value returned by succ_msg must exceed the value returned by pred_msg.

alert_msg format string to display when raising a constraint violation. b and 1 substitute for the predecessor and sucessor names, respectively. 11 substitutes for the delta value.

alert_action name of object to receive a tick! message when the tot_constraint object gets an alert! message.

MESSAGES

pred[=?] set or get the current predecessor name.

succ[=?] set or get the current successor name.

pred_msg[=?] set or get the predecessor message.

succ_msg[=?] set or get the successor message.

alert_action[=?] set or get the alert action.

alert_msg[=?] set or get the alert message. When queried, any 2.360738e-313scapes are substituted.

delta[=?] set or get the constraint delta.

draw! draw the constraint object.

update! notify the constraint object that either its predecessor or successor has changed.

alert! execute the alert_action.