[UVM foundation] UVM_ Driver member variable req definition

uvm_driver It is also a parameterized class , Should be defined in driver Specify this when driver To drive transaction The type of ：

class my_driver extends uvm_driver#(my_transaction);

The advantage of this definition is You can use it directly uvm_driver Some predefined member variables in , Such as uvm_driver There are member variables in req, Its type is passed to uvm_driver Parameters of , Here it is my_transaction, You can use it directly req：

Compared with before , There is no need to declare my_transaction, Direct instantiation req that will do ！

task my_driver::main_phase(uvm_phase phase);
   phase.raise_objection(this);
   vif.data <= 8'b0;
   vif.valid <= 1'b0;
   while(!vif.rst_n)
      @(posedge vif.clk);
   for(int i = 0; i < 2; i++) begin 
      req = new("req"); //  Use it directly req
      assert(req.randomize() with {
    pload.size == 200;});
      drive_one_pkt(req);
   end
   repeat(5) @(posedge vif.clk);
   phase.drop_objection(this);
endtask