Elemar´s Employee - http://bit.ly/1d8k32v

CanGrantBonus.cs

using Domain.Employees;
using Domain.Employees.BonusExtensions;

class CanGrantBonus
{
    public void Foo()
    {
        var employee = new Employee(
            name: "John Doe",
            salary: 1500
            );
 
        employee.GrantBonus(200);
    }
}

CanRaiseSalary.cs

using Domain.Employees;
using Domain.Employees.SalaryExtensions;

class CanRaiseSalary
{
    public void Foo()
    {
        var employee = new Employee(
            name: "John Doe",
            salary: 1500
            );
 
        employee.RaiseSalary(200);
    }
}

Employee.cs

namespace Domain.Employees 
{
	public class Employee
	{	
		public Employee(string name, decimal salary)
		{
			Name = name;
			Salary = salary;
		}
	 
		public string Name { get; private set; }
		public decimal Salary { get; internal set; }
	}
}

EmployeeBonusExtensions.cs

namespace Domain.Employees.BonusExtensions
{
	public static class EmployeeBonusExtensions 
	{
		public static void GrantBonus(this Employee employee, decimal amount)
		{
			employee.Salary += amount;
		}
	}
}

EmployeeSalaryExtensions.cs

namespace Domain.Employees.SalaryExtensions
{
	public static class EmployeeSalaryExtensions
	{
		public static void RaiseSalary(this Employee employee, decimal amount)
		{
			employee.Salary += amount;
		}
	}
}