Design Patterns in Modern C++: Reusable Approaches for Object-Oriented Software Design

© Dmitri Nesteruk 2018

Dmitri NesterukDesign Patterns in Modern C++https://doi.org/10.1007/978-1-4842-3603-1_3

3. Factories

Dmitri Nesteruk¹ 

(1)

St. Petersburg, Russia

 

I had a problem and tried to use Java, now I have a ProblemFactory.

–Old Java joke.

This chapter covers two GoF patterns at the same time: Factory Method and Abstract Factory. These patterns are closely related, so we’ll discuss them together.

Scenario

Let’s begin with a motivating example. Support you want to store information about a Point in Cartesian space. So you go ahead and implement something like this:

1   struct Point

2   {

3     Point(const float x, const float y)

4       : x{x}, y{y} {}

5     float x, y; // strictly Cartesian

6   };

So far, so good. But now, you also want to ...