We’ve already been through a brief introduction to design patterns, and a description of the most important creational design patterns and structural design patterns. In this article we’ll take a look at the last category of design patterns: behavioral patterns.

Behavioral design patterns are concerned with the relationships among communications using different objects. They identify common communication patterns and provide a well-known solution to implement this communication, offering a higher degree of flexibility.

The most used behavioral patterns are:

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We already saw what design patterns are and took a look at creational patterns in earlier articles. Today we’ll deal with the second category: structural patterns.

These design patterns are all about class and object composition. Class-creation patterns use inheritance to compose interfaces, whilst object patterns define ways to compose objects to obtain new functionality. All of these patterns aim to ease the design by identifying a simple way to realize relationships between entities.

The most common structural patterns are:

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In an earlier article we saw what design patterns are and how they can help us. Today we’re going to take a look at the first category: creational patterns.

Creational design patterns deal with class creation and instantiation, and how to use those instances. Basic class creation could result in design problems or added complexity to the design. These patterns solve these problems by controlling this object creation.

Some examples of creational design patterns:

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Design patterns are solutions to common software development problems, and aim to facilitate the development of a software project. A solution must have proven effectiveness and be highly reusable (can be applied to different design problems in different circumstances) to become a design pattern.

A pattern describes a problem that happens over and over again in our environment, and then explains the core of the solution to that particular problem. Since it is just a scheme of the solution, the application of this pattern is not literal: it requires adaptation. You could use the same pattern a thousand times, and never repeat the way you applied it.

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