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Last week I was asked a couple of questions about called base class constructors, to which I didn't know the answers. So, I did some digging. Firstly, Can you call super.new when there is no explicit constructor in the base class? To which the answer is: yes. I can't think why you'd want to, though. module M;     class C;     bit b;   endclass     class P extends C;     bit b;     function new;       super.new;     endfunction   endclass     C c = new;   endmodule https://www.edaplayground.com/x/3BB9 Can you call super.super.new? To which the answer is: no. Section 8.15 of IEEE 1800-2107 says "There is no way to reach higher (for example, super.super.count is not allowed)." module M;     class C;     bit b;   endclass     class P extends C;     bit b;   endclass;     class GP extends P;     bit b;     function new;       super.super.new;    // this line is illegal       super.new;     endfunction   endclass;     initial begin     GP gp;     g

A customer asked me whether you have a generic virtual interface, which could point at any kind of interface? eg    virtual interface vif; instead of    virtual APB_if vif; I would be nice perhaps. And you'd think it might be possible, because generic interface ports are possible. (See IEEE 1800-2017, section 25.3.3). However, this is one of those questions that I realise I know the answer to as soon as I try to start answering it.    virtual APB_if vif; is actually short for    virtual interface APB_if vif; (ie the " interface " is optional). So, because of that,    virtual interface vif; is clearly nonsense. IEEE 1800-2017, section 25.9 shows the syntax of a virtual interface:     virtual [ interface ] interface_identifier [ parameter_value_assignment ] [ . modport_identifier ]     interface I;       bit b;     endinterface     module M;         I i ();         // This line is NG:       //virtual interface vif1 = i;        

A customer asked me whether you could extend a concrete class into an abstract class, by adding a pure virtual function. It turns out you can. IEEE 1800-2012 section 8.21 confirms this: Any class may be extended into an abstract class, and may provide additional or overridden pure virtual methods. module M;     virtual class pure_virtual_base_class;     pure virtual function void foo;   endclass     class concrete_class extends pure_virtual_base_class;     virtual function void foo; endfunction   endclass     virtual class another_pure_virtual_base_class extends concrete_class;     pure virtual function void foofoo;   endclass      endmodule    https://www.edaplayground.com/x/2FpZ A customer asked me about this. I didn't know the answer, so I wrote a few lines of code on EDA Playground. EDA Playground is great for that, because it's always on. You don't have to queue for licences, wait for EDA tools to start, create new files, fire up editors...