The document discusses approaches to translating declarative operation specifications defined using the Object Constraint Language (OCL) into imperative implementations. It proposes using heuristics to disambiguate ambiguous postconditions and determine the intended outcome, and provides patterns for translating common OCL expressions into sequences of UML actions. Open issues include inherently ambiguous expressions and combining translation patterns for complex postconditions.

1. From Declarative to Imperative UML/OCL Operation Specifications Jordi Cabot Open University of Catalonia

4. Motivation: Expected behavior of GoalEvaluation ? context Department::GoalEvaluation() post : self.sumSales=self.employee.sales.amount->sum() and if self.sumSales>self.goal then self.employee->forAll(e| e.salary= e.salary@pre + e.category.raise) else self.carFleet->excludesAll(Car::allInstances->select(c| c.type=‘Luxury’)) endif Or where we change the category where the employee belongs to Final states where not referenced objects are modified also satisfy the postcondition Or final states where we assign a zero value to sumSales and remove all sales from the employees Or where we remove the employees of a department Or final states where the id of the department is modified Or when we add/remove non-luxury cars to the department (or remove all cars) If employees have sold enough to fulfill the goal, their salary is increased as indicated by their category. Otherwise, employees are not longer allowed to use luxury cars

5. Motivation OCL WORKSHOP at MODELS’06 -- withdraw gives the customer money if there is enough money in the account. The return value indicates whether the withdrawal was successful or not. context ATMController::withdraw(amount:Real) : Boolean post : if (amount <= customer.account.balance) then customer.account.balance = customer.account.balance@pre – amount result:=true . . . BOOK: The Object Constraint Language. Kleppe and Warmer context LoyaltyProgram::addService(p: ProgramPartner, s: Service) pre: partners->includes( p ) post: partners.deliveredServices->includes( s ) . . .

11. Now, what is the expected behavior of Goal Evaluation ? If employees have sold enough to fulfill the goal, their salary is increased as indicated by their category. Otherwise, employees are not longer allowed to use luxury cars context Department::GoalEvaluation() post : self.sumSales=self.employee.sales.amount->sum() and if self.sumSales>self.goal then self.employee->forAll(e| e.salary= e.salary@pre + e.category.raise) else self.carFleet->excludesAll(Car::allInstances->select(c| c.type=‘Luxury’)) endif

16. Imperative version of GoalEvaluation context Department::GoalEvaluation() { AddAttributeValue(sumSales, self, self.employee.sales.amount->sum()); if self.sumSales>self.goal then foreach e in self.employee AddAttributeValue(salary, e, e.salary@pre + e.category.raise); endfor; else foreach c in Car::allInstances->select(c| c.type=‘Luxury’) DestroyLink (DepartmentCar, self, c); endfor; endif }