Question

I have 3 classes, two inherit from 1:

public class Employee {
    private virtual double getBonus() { ... }
    private virtual double getSalary() { ... }
}

public class Nepotism : Employee {
    private double getBonus() { ... }
}

public class Volunteer : Employee {
    private double getSalary() { ... }
}

So the question is sometimes there will be a Volunteer who gets the Nepotism bonus – is there some way to write the constructors to allow overriding/nesting the base class like this:

Employee Bill = new Volunteer(new Nepotism());

I’m thinking something like:

public class Volunteer : Employee {
    private Employee _nest;
    public Volunteer(Employee nest) 
        : base() {
        _nest = nest;
        // now what?
    }
}

Basically I want some objects to have the overrides from both classes.

I would like to avoid writing the override methods to check for nested classes.

getSalary() {
    return (nest != null) ? nest.salary : salary; // I want to avoid this if I can
}

How can I do this? Am I on the right track? Am I off the rails?

Answer 1

I think you are trying to use inheritance in an ill-advised way. This approach creates a mess of dependences and oddball business rules, which results in a rigid architecture that is hard to use and maintain.

If calculating an employees salary is dependent upon the Employee as well as “bonus traits”, then it would be better to separate all three things from each other:

interface IBonusTrait
{
    decimal ApplyBonus(Employee employee, decimal currentTotal);
}

class Employee
{
    // ...

    public decimal BaseSalary { get; set; }
    public IList<IBonusTrait> BonusTraits { get; set; }
}

class SalaryCalculator
{
    public decimal CalculateSalary(Employee employee)
    {
        decimal totalSalary = employee.BaseSalary;
        foreach (IBonusTrait bonusTrait in employee.BonusTraits)
        {
            totalSalary = bonusTrait.ApplyBonus(employee, totalSalary);
        }

        return totalSalary;
    }
}