RE: [sv-ec] A question about mixing rand and non-rand handles to the same object

 When ch2.randomize() is called, the set of random objects 
and constraints initially consists of all the random members
and constraints of ch2. These are:
   Random variables:
  	ch2.rint2
	ch2.rch1
   Constraints:
	ch2.con2 {ch2.rint2 == ch2.ch1.rint1;}

Because ch2.rch1 is random and is a class handle, its
random members and constraints are added to the randomization.
So the random variable and constraints become:
   Random variables:
	ch2.rint2
	ch2.rch1.rint1
   Constraints:
	ch2.rch1.con1 { ch2.rch1.rint1 == 10; }
	ch2.con2 {ch2.rint2 == ch2.ch1.rint1;)

A reference to a variable in a constaint does not make it 'rand'. So
yes,
for this randomization, ch2.ch1.rint1 is a state value.

Ray

> -----Original Message-----
> From: owner-sv-ec@server.eda.org 
> [mailto:owner-sv-ec@server.eda.org] On Behalf Of William Paulsen
> Sent: Friday, September 29, 2006 1:29 PM
> To: sv-ec@server.eda-stds.org
> Subject: [sv-ec] A question about mixing rand and non-rand 
> handles to the same object
> 
> 
> Section 13.4.8 of the LRM is not clear (to me) about the 
> following scenario.
> Does there need to be an explanation or clarification added 
> to the LRM for this?
> 
> Thanks,
> Bill
> 
> 
> In the example below, two constraint expressions contain 
> references to the same property (rint1) of the same class 
> (class1) object instance.
> 
>   In class2, constraint "con2" has the reference "ch1.rint1", 
> where "ch1"
>   is not a rand handle.
> 
>   In class1, constraint "con1" has the reference "rint1", 
> where "rint1"
> is rand.
> 
> Is "ch1.rint1" in constraint "con2" considered a state 
> variable, or is it one of the "active random objects?"
> 
> One possibility is that in constraint "con2", "rint1" is a 
> state variable, whose value is not subject to generation, 
> since "ch1" is not rand.
> 
> The other possibility is that since "ch2.ch1.rint1" is the 
> same property as "ch2.rch1.rint1", then it should be 
> considered rand even in the context of constraint "con2".
> 
> module top;
> 
> class class1;
>   rand int rint1;
>   constraint con1 { rint1 == 10;}
> endclass
> 
> class class2;
>   rand int rint2;
>   class1 ch1;
>   rand class1 rch1;
>   constraint con2 { rint2 == ch1.rint1; } // What value is 
> rint2 set to?
> endclass
> 
> class2 ch2 = new;
> int res;
> 
> initial begin
>   ch2.ch1 = new;
>   ch2.rch1 = ch2.ch1;  // The same object
> 
>   ch2.ch1.rint1 = 20;
> 
>   res = ch2.randomize();
> 
>   if (ch2.rint2 == 20) $display("ch2.ch1 is considered non-rand");
>   if (ch2.rint2 == 10) $display("ch2.ch1 is considered 
> rand"); end endmodule
> 
> 
>