Template method pattern: Difference between revisions

Revision as of 11:48, 25 April 2023

Revision as of 14:32, 26 April 2023

Line 107:

==C++ example==

This C++14 implementation is based on the pre C++98 implementation in the book.

<syntaxhighlight lang="cpp">

#include<iostream>

<syntaxhighlight lang="cppc++">

// abstract

#include <iostream>

class BaseClass {

#include <memory>

protected:

virtual void someMethod() = 0;

class View { // AbstractClass

public:

// defines abstract primitive operations that concrete subclasses define to implement steps of an algorithm.

void ThisIsTemplateMethod() { someMethod(); }

virtual void someMethoddoDisplay() = 0;{}

// implements a template method defining the skeleton of an algorithm. The template method calls primitive operations as well as operations defined in AbstractClass or those of other objects.

void display() {

setFocus();

doDisplay();

resetFocus();

}

virtual ~View() = default;

private:

void setFocus() {

std::cout << "View::setFocus\n";

}

void resetFocus() {

std::cout << "View::resetFocus\n";

}

};

class ExtendedClass_oneMyView : public BaseClassView { // ConcreteClass

// implements the primitive operations to carry out subclass-specific steps of the algorithm.

protected:

void someMethoddoDisplay() override {

// render the view's contents

puts("[ExtendedClass_one] Re-Define method here.");

std::cout << "MyView::doDisplay\n";

}

};

class ExtendedClass_two : public BaseClass {

protected:

void someMethod() override {

puts("[ExtendedClass_two] Re-Define method here.");

}

};

int main() {

// The smart pointers prevent memory leaks

std::unique_ptr<View> myview = std::make_unique<MyView>();

myview->display();

}

</syntaxhighlight>

The program output is

BaseClass* one = new ExtendedClass_one;

one->ThisIsTemplateMethod();

<syntaxhighlight lang="c++">

BaseClass* two = new ExtendedClass_two;

View::setFocus

two->ThisIsTemplateMethod();

MyView::doDisplay

View::resetFocus

return 0;

}

</syntaxhighlight>