RE: [sv-cc] vpiVirtualInterfaceVar and vpiClassVar as vpiRefObj

Radek, it depends on the mental model of what these objects are.

I think (although I was not part of the original definition) that a vpiRefObj is effectively an alias for another object -- at least at certain points in simulation time.  It is in fact intended to be "different from" the actual instantiated object: "The vpiActual relationship always returns the actual instantiated object if the ref obj is bound to an actual object at the time of the query."

Note that this raises another reason for keeping "C.i" separate.  At some points in simulation time, the class variable "C" is not bound to an actual class object.  So at those times, "C.i" is also not bound to a variable in an actual class object.

So I expect that these are the reasons that selected elements of a ref obj are also ref objs.

Regards,
Jim Vellenga

From: owner-sv-cc@eda.org [mailto:owner-sv-cc@eda.org] On Behalf Of Radoslaw Nawrot
Sent: Tuesday, December 17, 2013 4:33 AM
To: sv-cc@eda.org
Subject: [sv-cc] vpiVirtualInterfaceVar and vpiClassVar as vpiRefObj

Hi All,
I was thinking about part of LRM:

"A ref obj represents a declared object or subelement of that object that is a reference to an actual instantiated object.

A ref obj exists for ports with ref direction, for an interface port, a modport port, or for formal task function ref

arguments. The specific cases for a ref obj are as follows:

- A variable, named event, named event array that is the lowconn of a ref port

- Any subelement expression of the above

- A local declaration of an interface or modport passed through a port or any net, variable, named event, named

event array of those

- A ref formal argument of a task or function, or subelement expression of it

"
I have an example:


module top;
 class C;
  int i;
 endclass
 function automatic void afct(ref C c);
  $vpiF(c.i);
 endfunction

 C x=new;

 initial #2 afct(x);

endmodule

Is "c.i" really a ref object ? "i" is a part of vpiClassObj not vpiClassVar.
Should LRM exclude from being ref object class and virtual interface member's ?

Regards,
Radek


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