Aquivalent References as in C++?

[Namespace]

> Yes, you must because whetheer obj is null is only known at 
> runtime.

Yes, but if i forget the assert i get an Access Violation error 
with no more informations. Problem is nobody knows _why_ he gets 
this error, because the error message gives no information.
So it must be a better solution then to write in every method 
"assert(obj_param !is null");". Best of all solutions would be 
that a special keyword, for example  scope, ensure that lvalues 
would except but _no_ null-references.