Returning the Default on Generic Types
Friday, May 18, 2007 2:37:24 AM (Mountain Standard Time, UTC-07:00)
So during my quest to understand NHibernate I came across a new keyword in C#. (well kind of new, it's actually an old keyword but used in a different manner specifically for generic types.)
Here's my problem... When you define a generic type it does not assume it to be either of a reference type or value type. And I do not want to force my type to be a reference type, I want it to be generic. But in a scenario where I have to return an blank or "null" value, that assumption says that the type has to be a reference type...
Here's what I'm talking about:
The return null statement is making the assumption that T is a reference type. (I don't want to make this assumption!) In this case I would like to return the default value for reference types and value types without having to create 2 generic types. One for each!
So I can use the default( T ) statement which will return a null for reference types, and a 0 for value types! Problem solved.
public T SearchFor( Int32 id ) {
using( ISessionTransaction dbStore = _manager.StartTransaction( ) ) {
try {
return ( T )dbStore.Session.Load( typeof( T ), id );
}
catch( ObjectNotFoundException ) {
return default( T );
}
catch( ADOException ) {
if( dbStore != null && null != dbStore.Transaction ) {
dbStore.Transaction.Rollback( );
}
throw;
}
}
}
See MSDN for more information...
http://msdn2.microsoft.com/en-us/library/xwth0h0d(VS.80).aspx
