Re: Am I using NVI?

Dragan Milenkovic <>
Thu, 18 Jun 2009 12:45:32 CST
Martin T. wrote:

DeMarcus wrote:

In The C++ Programming Language 3rd ed. by Stroustrup, p.314 it explains
the use of pure virtual interfaces.

In C++ Coding Standards by Sutter & Alexandrescu it says:
Item 39: Consider making virtual functions nonpublic, and public
functions nonvirtual.


Personally I have used it when it comes naturally (i.e. the Base class
need to do work before and after the virtual function anyway) and if I
just have an interface like the one you have above, I'll leave it at that.

Don't know if it helps or if I'm right, but I _always_ consider
delegation first. Of course, sometimes such design doesn't make sense...

My arguments are - separation of responsibilities, encapsulation...

class NVI_Base {
     void func() {

     virtual void work() = 0;


class NVI_Concrete {
     explicit NVI_Concrete(Worker * worker);

     void func() {
     Worker * worker;

class Worker {
     virtual void work() = 0;

Usually, Worker::work gets a state as an argument.

Maybe you could give a concrete example for analysis?


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