ab334bdd   
   From: daniel.kruegler@googlemail.com   
      
   On 2011-08-25 01:44, linq936 wrote:   
   > Hi,   
   > The question just came to me and could not find an answer.   
   >   
   > Normally we do not declare constructor and destructor in pure class   
   > and compiler generates them, but since the class is pure, compiler   
   > should declare the destructor as virtual, isn't it?   
      
   No. You can have a pure class that does not have a virtual destructor. A   
   pure function just prevents that you can construct an object of this class.   
      
   > class Base {   
   >     public:   
   >        virtual void do_sth() = 0;   
   > };   
   >   
   > class D {   
   >     public:   
   >        virtual void do_sth() {}   
   >   
   >      ... some other things ...   
   > };   
   >   
   > int main()   
   > {   
   >    Base* p = new D();   
   >    p->do_sth();   
   >    delete p;   
   >    return 0;   
   > }   
   >   
   > We write above sort of code a lot, if the destructor generated by   
   > compiler is not virtual, there will be memory leak.   
   >   
   > Can you confirm?   
      
   I can confirm that you might have a memory leak, if you rely on that   
   assumption ;-)   
      
   Note that pure class types are not necessarily constructed via new   
   expressions, e.g. we could write   
      
   int main()   
   {   
       D d;   
       Base* p = &d;   
       p->do_sth();   
   }   
      
   In this example there is no need for a virtual destructor.   
      
   HTH & Greetings from Bremen,   
      
   Daniel Krügler   
      
      
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