Making a custom class availabe to LINQ queries [duplicate]

Question

I have a basic collection class that simply wraps a list of a custom object, held in a List variable to allow me to use this[] indexing.

However, I now want to make the class accessible for be able to run from item in collection LINQ queries

Using a simplified analogy, I can get a staff member from the list by just doing

Employeex = MyStaffList[Payroll];

...but what I now want to do is

var HREmps = from emp in StaffList
             where emp.Department == "HR"
             select emp;

Below is proto-type class definition....

public class StaffList
{
    List<Employee> lst = new List<Employee>();

    public StaffList()
    {
        /* Add Employees to the list */
    }

    public Employee this[string payroll]
    {
        get
        {
            Employee oRet = null;
            foreach (Employee emp in lst)
            {
                if (emp.Payroll.Equals(payroll, StringComparison.InvariantCultureIgnoreCase))
                {
                    oRet = emp ;
                    break;
                }
            }
            return (oRet);
        }
    }
}

public class Employee
{
    public string Payroll;
    public string Department;
    .
    .
    .
    .
}

Answer 1

You need to make your class implement IEnumerable<Employee> in order to enable LINQ. That's easy enough to do (there is only one method and it can just return lst.GetEnumerator();.

However, what is even easier is to derive from List<Employee> directly instead of deriving from object. Is there a reason you don't do that?