C++Guns – RoboBlog blogging the bot

27.10.2017

C++ Guns - multi derived CRTP - more pain

Filed under: Allgemein — Tags: — Thomas @ 19:10

And because we love pain, here come the CRTP diamond derive.
Have fun with these. (no, don't)

  #include <iostream>

  using namespace std;

  template<typename Child, typename Child2>
  struct UltraBase : public Child, public Child2 {
    void func() {
      cout << "UltraBase\n";
      static_cast<Child*>(this)->func();
    }
    
    void func2() {
      cout << "UltraBase\n";
      static_cast<Child2*>(this)->func2();
    }
  };
  
  template<typename Child>
  struct Base : public Child {
    void func() {
      cout << "Base\n";
      static_cast<Child*>(this)->func();
    }
  };

  template<typename Child>
  struct Base2 : public Child {
    void func2() {
      cout << "Base2\n";
      static_cast<Child*>(this)->func2();
    }
  };

  struct Child {
    void func() {
      cout << "Child\n";
    }
    
    void func2() {
      cout << "Child2\n";
    }
  };


  int main() {
    UltraBase<Base<Child>, Base2<Child>> ultrabase;
    ultrabase.func();
    ultrabase.func2();
  }

UltraBase
Base
Child
UltraBase
Base2
Child2

C++ Guns - multi derived CRTP

Filed under: Allgemein — Tags: — Thomas @ 19:10

As we all know, CRTP is bad. The reasons against you can read on my unpublish Artikel "Why CRTP is a bad choise".

Nevermind. Here come a CRTP with a linear derived chain.

#include <iostream>

using namespace std;

template<typename Child>
struct Base : public Child {
  void func() {
    cout << "Base\n";
    static_cast<Child*>(this)->func();
  }
};

template<typename Child>
struct Base2 : public Child {
  void func() {
    cout << "Base2\n";
    static_cast<Child*>(this)->func();
  }
};

struct Child {
   void func() {
     cout << "Child\n";
   }
};


int main() {
  Base<Base2<Child>> base;
  base.func();
}

Base
Base2
Child

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