In reply to new_to_uvm:
The uvm_field macros do not support fields of every type. We strongly do not recommend using them because they are terrible for performance. See http://verificationhorizons.verificationacademy.com/volume-7_issue-2/articles/stream/are-ovm-and-uvm-macros-evil-a-cost-benefit-analysis_vh-v7-i2.pdf