What is the curiously recurring template pattern (CRTP)?

Question

Without referring to a book, can anyone please provide a good explanation for CRTP with a code example?

Answer 1

Just as note:

CRTP could be used to implement static polymorphism(which like dynamic polymorphism but without virtual function pointer table).

#pragma once
#include 
template 
class Base
{
    public:
        void method() {
            static_cast(this)->method();
        }
};

class Derived1 : public Base
{
    public:
        void method() {
            std::cout << "Derived1 method" << std::endl;
        }
};


class Derived2 : public Base
{
    public:
        void method() {
            std::cout << "Derived2 method" << std::endl;
        }
};


#include "crtp.h"
int main()
{
    Derived1 d1;
    Derived2 d2;
    d1.method();
    d2.method();
    return 0;
}

The output would be :

Derived1 method
Derived2 method