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.
