Re: Mix Static and dynamic Polymorphism

From:

Maxim Yegorushkin <maxim.yegorushkin@gmail.com>

Newsgroups:

comp.lang.c++.moderated

Date:

Sat, 7 Nov 2009 18:24:34 CST

Message-ID:

<4af5ddae$0$9752$6e1ede2f@read.cnntp.org>

On 07/11/09 15:16, Jun wrote:

Hello all,

I just tried to mix static and dynamic polymorphism together.

I've a vector to store all the elements, and the implementations
of elements are slightly different. I used Policy-based design:

struct Interface{
    virtual void run(void) = 0;
    virtual void execute(void) = 0;
};

struct PolicyA{
    void execute(){
       // implementing Policy A;
    }
};

struct PolicyB{
    void execute(){
       // implementing Policy B;
    }
};

template<class Policy>
struct Base : public Policy, public Interface{
     void run(){
          // implementing base ;
     }
}

Anyway, those codes don't compile .... Anyone has some suggestions ?
Thank you in advance.

You could try inheritance chaining:

   struct Interface {
      virtual void run() = 0;
      virtual void execute() = 0;
   };

   template<class Itf>
   struct PolicyA : Itf {
      void execute() {
         // implementing Policy A;
      }
   };

   template<class Itf>
   struct PolicyB : Itf {
      void execute() {
         // implementing Policy B;
      }
   };

   template<class Policy>
   struct Base : Policy {
       void run(){
            // implementing base ;
       }
   };

   typedef Base<PolicyA<Interface> > BaseA;
   typedef Base<PolicyB<Interface> > BaseB;

   int main()
   {
       Interface const& a = BaseA();
       Interface const& b = BaseB();
   }

--
Max

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