Static and Parameterized Gotchas

Overview

Statics and parameterized classes interact in surprising ways: base-class statics can be globally shared, and shallow clones can alias nested handles across seemingly independent wrappers.

A team expected pkt#(int) and pkt#(byte) counters to restart independently. IDs interleaved in logs, causing flaky ordering assertions. Root cause was static next_id declared in a non-parameterized base class, making it shared for every specialization.\n\nA second issue appeared in the same flow: wrappers were cloned shallowly, so payload handles were shared across predictor and scoreboard. Engineers thought specialization separated state, but aliasing ignored type boundaries because both wrappers referenced the same underlying object.

In this topic

1. Concept Explained
2. Code Examples
3. SystemVerilog vs C++/Java
4. Pitfalls
5. Exercises
6. Interview Questions

Read the concept first, study the code examples, compare against C++/Java, then test yourself with the exercises and interview questions.

OOP bug root-cause decision tree

ROOT CAUSE TREE FOR OOP FAILURES

symptom: test behavior mismatch
                 |
           reproducible?
            /       \
          no         yes
          |           |
   check race/time   inspect object state
                      /        |        \
                 null handle  aliasing  wrong override
                    |            |           |
               construct path  clone policy  virtual+factory map
                    \           |           /
                     +------ implement fix ------+

Localize the failing object lifecycle before broad refactoring.

Related topics

• Tricky Pitfalls & Debug section

• SystemVerilog OOP Mastery hub