You Gotta Constrain to Expand...

When you create a Generic class and constrain the Type parameter T, you are actually increasing the number of operations available. I know it sounds like a contradiction but it makes sense when you think about it. By constraining my Type parameter with an Interface for example, I get access to all the operations that Interface defines. If you do not apply a constraint then you are limiting yourself to operations on System.Object!

Quick example...

    
    public interface IPerson
    {
        int Age { get; set; }
    }

    public class PersonRepository<T> where T : IPerson
    {
        private T m_person;

        public PersonRepository(T person)
        {
            this.m_person = person;
        }

        public void Save()
        {
            // The Age property is available
            if (this.m_person.Age > 65)
            {
                // Save to free bus pass database...
            }
        }
    }