Can you explain what it means to create an instance using the template method?

Creating an instance using the Template Method pattern is a design pattern that defines the skeleton of an algorithm in a base class, while the specific steps of the algorithm are implemented in subclasses.

That is, the base class contains a method that sets the sequence of calls to other methods (the template), some of which can be abstract or virtual so that subclasses can override them.

Example in C++:

#include <iostream>

class AbstractClass {
public:
    void TemplateMethod() {
        Step1();
        Step2();
        Step3();
    }

protected:
    void Step1() { std::cout << "General step 1\n"; }
    virtual void Step2() = 0; // Step to be implemented by subclass
    void Step3() { std::cout << "General step 3\n"; }
};

class ConcreteClass : public AbstractClass {
protected:
    void Step2() override {
        std::cout << "Concrete implementation of step 2\n";
    }
};

int main() {
    ConcreteClass obj;
    obj.TemplateMethod();
    return 0;
}

In this example, TemplateMethod sets the order of calling steps, and the specific step Step2 is implemented in the subclass. This allows reusing the algorithm structure and changing details in subclasses.