RE: [sv-ac] question about classes as local variables in properties and sequences

I think that this is what we agreed on with Manisha, but will all agree?
ed
 


________________________________

	From: Bassam Tabbara 
	Sent: Tuesday, July 11, 2006 5:52 PM
	To: Kulshrestha, Manisha; Eduard Cerny
	Cc: sv-ac@eda-stds.org
	Subject: RE: [sv-ac] question about classes as local variables
in properties and sequences
	
	
	Hi Ed/Manish,
	 
	It's the following: 1533: LRM not clear about types of local
variables in properties and sequences 
	 
	State that ones allowed are those of Boolean expressions. 
	 
	Thx.
	-Bassam.
	 

________________________________

	From: owner-sv-ac@eda-stds.org [mailto:owner-sv-ac@eda-stds.org]
On Behalf Of Kulshrestha, Manisha
	Sent: Tuesday, July 11, 2006 2:45 PM
	To: Eduard Cerny
	Cc: sv-ac@eda-stds.org
	Subject: RE: [sv-ac] question about classes as local variables
in properties and sequences
	
	
	Yes, I think so. Unless someone thinks that we should allow
other types also.
	 
	Manisha

________________________________

	From: Eduard Cerny [mailto:Eduard.Cerny@synopsys.com] 
	Sent: Tuesday, July 11, 2006 2:42 PM
	To: Kulshrestha, Manisha
	Cc: sv-ac@eda-stds.org
	Subject: RE: [sv-ac] question about classes as local variables
in properties and sequences
	
	
	Manisha,
	 
	would this fit as a proposal in on of the errata that you filed
today?
	 
	ed
	 


________________________________

		From: Kulshrestha, Manisha
[mailto:Manisha_Kulshrestha@mentor.com] 
		Sent: Tuesday, July 11, 2006 4:56 PM
		To: Eduard Cerny; sv-ac@eda-stds.org
		Subject: RE: [sv-ac] question about classes as local
variables in properties and sequences
		
		
		Hi Ed,
		 
		I think it would be fine to state it in the LRM that
local variables can be only of the same type as those that can be used
in boolean expressions.
		 
		Thanks.
		Manisha

________________________________

		From: Eduard Cerny [mailto:Eduard.Cerny@synopsys.com] 
		Sent: Tuesday, July 11, 2006 12:02 PM
		To: Kulshrestha, Manisha; sv-ac@eda-stds.org
		Subject: RE: [sv-ac] question about classes as local
variables in properties and sequences
		
		
		Hi Manisha,
		 
		my understanding woudl be that local variables can be
only of the same type as those that can be sampled in the boolean
expressions. That is, no class types. I suppose that we could extend it,
so that a call to new is implicit anytime an instance is to be created,
like for the integral types of local variables. That to me seems quite
feasible. Is it needed?
		The question is, what if a task in the property copies
the handle to some other global variable. Normally, the instance of a
variable created in a property thread disappears when the thread dies.
Should the instance be preserved in this case? Or would it allow only a
deep copy to a global variable of that class type?  Etc...
		 
		Best regards,
		ed


________________________________

			From: owner-sv-ac@eda-stds.org
[mailto:owner-sv-ac@eda-stds.org] On Behalf Of Kulshrestha, Manisha
			Sent: Tuesday, July 11, 2006 2:41 PM
			To: sv-ac@eda-stds.org
			Subject: [sv-ac] question about classes as local
variables in properties and sequences
			
			
			Hi All,
			 
			I have few questions regarding usage of classes
in assertions:
			 
			1. Currently LRM does not allow the boolean
expressions in assertions to have class as per section 17.4.1. But there
is no restriction on having a local variable as a class. So, is it
allowed to have a local variable of type class in the assertion
expression ? 
			 
			2. Currently section 17.4.1 lists all the types
which are not allowed to be in the boolean expressions. What are the
main reasons for this restriction ? Is it mainly driven by sampling
issues or there are other issues ?
			 
			3. Consider the following example with a local
variable of type class (called myClass. myClass has a data member called
myData):
			 
			sequence S;
			  myClass lv;
			 
			(a, lv = new()) ##1 ((seq1, lv.myData = 0) or
(seq2, lv.myData = 1)) ##1 (d, $display("value of myData is %b",
lv.myData));
			 
			endsequence
			 
			As per LRM section 17.8, each branch of 'or'
should have its own copy of lv and assign to it. But here, there is only
one 'new' on lv so both the branches of 'or' will refer to the same
local variable (because lv behaves like a pointer).
			 
			Currently LRM does not clarify how copies of the
variables should be created in case of branching for classes and other
objects which behave like pointers. 
			 
			Any inputs ?
			 
			Thanks.
			Manisha