In trying to centralize how items are added, or removed from my business entity classes, I have moved to the model where all lists are only exposed as ReadOnlyCollections and I provide Add and Remove methods to manipulate the objects in the list.

Here is an example:

```
public class Course
{
    public string Name{get; set;}
}

public class Student
{
    private List<Course>_courses = new List<Course>();
    public string Name{get; set;}
    public ReadOnlyCollection<Course> Courses {
        get{ return _courses.AsReadOnly();}
    }
    public void Add(Course course)
    {
        if (course != null && _courses.Count <= 3)
        {
            _courses.Add(course);
        }
    }
    public bool Remove(Course course)
    {
        bool removed = false;
        if (course != null && _courses.Count <= 3)
        {
            removed = _courses.Remove(course);
        }
        return removed;
    }
}

```

Part of my objective in doing the above is to not end up with an Anemic data-model (an anti-pattern) and also avoid having the logic that adds and removes courses all over the place.

Some background: the application I am working with is an Asp.net application, where the lists used to be exposed as a list previously, which resulted in all kinds of ways in which Courses were added to the Student (some places a check was made and others the check was not made).

But my question is: is the above a good idea?