Master Software Design Patterns and Architecture in C++/

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Solution: CRTP-derived Class Restriction

Solution: CRTP-derived Class Restriction

Get a detailed explanation of the solution to the CRTP-derived class restriction exercise.

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Solution

C++
#include <iostream>
template <typename Derived>
struct Base{
  void interface(){
    static_cast<Derived*>(this)->implementation();
  }
private:
    Base() = default;             
    friend Derived;               
};
struct Derived1: Base<Derived1>{
  void implementation(){
    std::cout << "Implementation Derived1" << '\n';
  }
};
struct Derived2: Base<Derived2>{   
  void implementation(){
    std::cout << "Implementation Derived2" << '\n';
  }
};
template <typename T>
void execute(T& base){
    base.interface();
}
int main(){
  
  std::cout << '\n';
  
  Derived1 d1;
  execute(d1);
    
  Derived2 d2;
  execute(d2);
  
  std::cout << '\n';
  
}

Explanation

  • Lines 8–9: We defined a private base class constructor. Because it’s private, only a
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