The Object Model
In our example, the object model includes companies that take part in projects. A company is composed of several departments, each employing a number of people who contribute to the projects. Each department has a manager. A manager is a specific kind of employee. Employees, employee contributions and projects have a cost, which is calculated as follows:
-
Cost of an employee = monthly salary of the employee x the number of months spent on all projects
-
Cost of a contribution = monthly salary of the employee x the number of months spent on the contribution
-
Cost of a project = sum of the contribution costs
The object model can be coded as follows:
class Company: public IlsEntity
{
public:
IlsUsesList<Company,Project> projects;
IlsOwnsList<Company,Department> departments;
};
class Department: public IlsObject
{
public:
IlsEntry<IlsString> name;
IlsOwnsList<Department,Employee> employees;
IlsUses<Departement,Manager> manager;
IlsInvertedRelation<Department,Company> company;
};
class Employee: public IlsObject
{
public:
IlsEntry<IlsString> name;
IlsEntry<int> monthCost;
IlsDerived<Employee,int,NbMonthsEvaluator> nbMonths;
IlsDerived<Employee,int,CostEvaluator> cost;
IlsInvertedRelation<Employee,Department> department;
IlsInvertedRelationList<Employee,Contribution> contributions;
};
class Manager: public Employee
{
};
class Project: public IlsEntity
{
public:
IlsOwnsList<Project,Contribution> contributions;
IlsInvertedRelationList<Project,Company> companies;
IlsDerived<Project,int,CostEvaluator> cost;
};
class Contribution: public IlsObject
{
public:
IlsUses<Contribution,Employee> employee;
IlsInvertedRelation<Contribution,Project> project;
IlsEntry<int> nbMonths;
IlsDerived<Contribution,int,CostEvaluator> cost;
};
Figure 7.1 shows the class diagram of this object model.
The Company Object Model in IBM Rational Rose Modeler
Figure 7.2 illustrates an instance of the model.
