Requirements for overriding GetHashCode

The following are the requirements to remember when  you override GetHashCode System.Object function: 

• Two equal objects must have equal hash codes
• The Hash code of a particular object must never change (you might want to cache the result. In NHibernate's case you should use the primary keys to generate it since they do not change)
• It should not throw exceptions 

That's it. Plain and simple.

Enjoy!