There are a number of problems in section 7.19 that need to be addressed, Ideally, I would have liked to address each issue separately, but the text is so intertwined that it was too difficult to come up with separate proposals. I'll list the separate proposals that this single proposal addresses. 1. Abstract classes and virtual methods are two separate features and need to be defined independently. It would be best to split virtual methods from abstract classes and describe them in their own section. They were only bundled in one section because they use the same keyword "virtual", but that is not a good reason. Prototype virtual methods belong with abstract classes. This is a clarification. 2. We need to distinguish between the instantiation of a class object and its handle. You declare class handles and construct class objects. It should be legal to declare abstract class handles, but not construct abstract class objects (i.e. call the new operator). I think this was the actual intent, and this is just a clarification 3. We need to clarify what a matching prototype for virtual method is. This is an erratum. I am proposing that types must match, but formal identifiers and defaults do not need to match. 4. What exactly is a virtual method without an implementation?. The example shows a function without a statement body, but that function has an implementation and is callable by Verilog standards. If I look at Vera, it uses the same syntax as a prototype for an out-of-class-body prototype to denote a virtual method without an implementation, so I am suggesting we use the same extern syntax as we do in SystemVerilog. This is a major hole in the LRM and will require a BNF change. 5. The old text is written in an informative style in a normative section. Because of that, the rules about the interaction between abstract classes and prototype virtual methods are not clear at all. I've tried to clean that up where I could. I've attached two versions of the proposal; one with markups, and one without for easier reading. Thanks, Dave David Rich Verification Technologist Design Verification & Test Division Mentor Graphics Corporation dave_rich@mentor.com Office: 408 487-7206 Cell: 510 589-2625
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