Have you ever tried to read bursts of data from any memory model before even writing any data? If so, you had to encounter “x” from all read addresses. Of course, this ”x” is not valid data to be read.
If you are trying to model out a bidirectional mux, the tranif primitives might be more appropriate to use.
If you give a specific name to your error message, you can turn it off later on. This may be useful in a case where you want to see simulation behavior with only this checker turned off or if you want to run a test that ignores a certain error.
Every class object can contain properties, methods or other class instantiations as part of it. There is always a need to copy content from one group to another.