Can I have a virtual function that must be overridden from a non-abstract base

Question

Say I have base and derived classes

class MyBaseClass
{
public:
   virtual void MustBeOverRidden()
   { 
      DoSomething();
   }
};

class MyDerivedClass : public MyBaseClass
{
public:
   void MustBeOverRidden()
   { 
      MyBaseClass::DoSomething();
      DoSomethingElse();
   }
};

if BaseClass was abstract, I could declare

  virtual void MustBeOverRidden() = 0;

however in this case the base class functionality will typically be called as part of the derived functionality. Is there any way to force all derived classes to override the base class function in this case? Alternatively, can I provide an implementation for a pure virtual function?

Edit: Implementation for a pure virtual function does not work as I need to be able to instantiate my base class, which results in error C2259: 'MyBaseClass' : cannot instantiate abstract class

Do you mean `class MyDerivedClass : public MyBaseClass`? – HAL Aug 09 '13 at 08:20 — HAL, Aug 09 '13 at 08:20

score 3 · Answer 1 · answered Aug 09 '13 at 08:20

3

Yes, it it possible to force derived classes to override a virtual function, and also provide an implementation:

class MyBaseClass
{
public:
   virtual void MustBeOverRidden() = 0;
};

void MyBaseClass::MustBeOverRidden()
{ 
    DoSomething();
}

answered Aug 09 '13 at 08:20

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The base class is still abstract when you do this. – user207421 Aug 09 '13 at 08:45

Can I have a virtual function that must be overridden from a non-abstract base

1 Answers1