RE: [sv-ec] Re: [sv-bc] operators and data type compatibility rules

Gordon, Dave, Steve,
 
I want to enter a mantis item for fixing this issue in the LRM.
 
So do I hear that the consensus is 
 
1) for equality == and inequality != operators we require that:
  the class datatypes of left operand and right operand either match
(this is superseeded by the next 2 rules)
 or that left operand is assignment compatible with right operand 
 or that right operand is assignment compatible with left operand?
 
  The rule is that left operand is assignment compatible with right
operand or right operand is assignment compatible with left.
 
  This means that we cannot compare class handles which are not of the
same class hierarchy. Is that really what we want?
 
 
2) For the conditional operator, if the condition is X we require that
if the true and false expressions are of class types, 
    either the left operand must be assignment compatible with the right
operand,
    or the right operand must be assignment compatible with the left
operand.
 
   if the condition is x, and the right operand is assignment compatible
with the left operand, the result is the left operand (base)
   if the left operand is assignment compatible with the right operand,
the result is the right operand (base),
   otherwise the result is null (default initialized value for class
data types).
 
  what about if both left and right have matching class data types?
which arm do we return? Do we do class handle
  comparison and if they are the same return the class handle (result
type is the class data type of either arm)
  and if the class handles are not the same, return null (result type is
irrelevant for null).
 
Francoise
       '
 
 
 



________________________________

	From: Vreugdenhil, Gordon [mailto:gordon_vreugdenhil@mentor.com]

	Sent: Saturday, September 16, 2006 1:12 AM
	To: Rich, Dave; Steven Sharp; Francoise Martinolle
	Cc: sv-bc@eda.org; sv-ec@eda.org; Vreugdenhil, Gordon
	Subject: RE: [sv-ec] Re: [sv-bc] operators and data type
compatibility rules
	
	



	That would be fine with me too.  I think that it is overly
	restrictive to require matching, but having a guarantee
	of a common base is sufficient in practice and gives a
	reasonable basis for implementation.
	
	Gord.
	
	-----Original Message-----
	From: Rich, Dave
	Sent: Fri 9/15/2006 9:57 PM
	To: Steven Sharp; fm@cadence.com; Vreugdenhil, Gordon
	Cc: sv-bc@server.eda.org; sv-ec@server.eda.org
	Subject: RE: [sv-ec] Re: [sv-bc] operators and data type
compatibility rules
	
	>
	> Another solution would be to require one of the expressions to
have a
	> type that is assignment compatible with the other.  Whichever
one can
	> be assigned from the other (i.e. the base class) is the type
of the
	> result.
	>
	>
	[DR>] I think this is the best solution. It is also what is
needed for b==c. The two classes much match, or one has to be on an
upwards path in the class hierarchy.