title: difference between std::randomize and class based randomize
body: <p>What is the difference between option A and Option B</p>
  
  <h2>Option A:</h2>
  
  <pre><code>sucess = std::randomize(type_l) with { 
     type_l inside { A ,B ,C};
     type_l dist { A := 2 ,B := 5 ,C := 4 }; 
  };
  
  if(  sucess == 0 ) begin
     `uvm_fatal("TEST_CFG", "type_l randomization failed")
  end
  </code></pre>
  
  <h2>Option B:</h2>
  
  <pre><code>class gen_type;
  
     enum_type type_l;
  
     constraint type_c{ 
        type_l inside { A ,B ,C};
        type_l dist { A := 2 ,B := 5 ,C := 4 }; 
     };       
  endclass
  </code></pre>