create() and new() in UVM

In UVM (Universal Verification Methodology), object creation is a very common operation. While writing testbenches, there are two ways of creating objects:

  • Using the constructor new()
  • Using the factory method create()

Although both are used to create objects, they serve very different purposes in UVM. Understanding this difference is critical for writing reusable, scalable, and factory-override friendly testbenches.

new() in UVM

new() is the standard SystemVerilog constructor used to directly create an object of a specific class.

Key Points

  • Creates an object directly
  • Bypasses the UVM factory
  • Object type is fixed at compile time
  • Factory overrides will NOT work

Example:

my_driver drv;

drv = new("drv");

create() in UVM

create() is a UVM factory-based method used to create objects via the UVM factory.

Key Points

  • Object is created through the factory
  • Supports type and instance overrides
  • Enables reusability and configurability
  • Recommended for all UVM components and sequence items

Example:

my_driver drv;

drv = my_driver::type_id::create("drv", this);

Why UVM Prefers create()

  • One of UVM’s biggest strengths is factory override.
  • Using create() allows you to replace a component without changing existing code.

Tip: Always use create() for UVM components and sequence items.
Use new() only for simple, non-factory objects.

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