Gain insights into software design patterns in C, explore their implementation, discover underlying principles, and learn to build a vocabulary for better communication and coding practices.

c.tar.gz

main+customer.c

main+customer.c-copy

watches

customers

observer

Reactor

Reactor-copy

observer-copy

Software design patterns are a valuable tool in any software developer's skill set. However, most design patterns are described in the context of an object-oriented programming language such as C++ or Java. The C language is sadly absent in the pattern literature. This course is here to change that by demonstrating that it is possible to use patterns in C programs and how it adds benefits to C programmers. You will learn why design patterns are more of a communication tool than technical solutions, and how patterns let you build and share a common vocabulary that simplifies communication.

The course presents a number of patterns and explains how to implement them in C. Each pattern is introduced via the problem it solves and the domains where the pattern can be used. We also discuss the underlying design principles as well as the trade-offs when applying the pattern. Finally, the course covers a set of coding idioms that will guide you when applying design patterns in C.

Software Design Patterns in C

The intent of the **Reactor** pattern is: “**The Reactor architectural pattern allows event-driven
applications to demultiplex and dispatch service requests that are delivered to an application from one or
more clients**” [(Schmidt et al)](https://www.educative.io/courses/software-design-patterns-c/conclusion).

The roles of the involved participants are:
* **EventHandler**: An EventHandler defines an interface to be implemented by modules reacting to
events. Each EventHandler owns its Handle.
* **Handle**: An efficient implementation of the **Reactor** pattern requires an OS that supports handles
(examples of Handles include system resources like files, sockets, and timers).
* **DiagnosticsServer** and **DiagnosticsClient**: These two are concrete event handlers, each one encapsulating
one responsibility. To be able to receive event notifications, the concrete event
handlers have to register themselves at the Reactor.
* **Reactor**: The Reactor maintains registrations of EventHandlers and fetches the associated Handles.
The Reactor waits for events on its set of registered Handles and invokes the corresponding
EventHandler as a Handle indicates an event.

In this lesson, we will explain the implementation of the Reactor pattern in the C language.


Implementing the Reactor Pattern - Part 1

In this lesson, we will explain the implementation of the Reactor pattern in the C language.

Introduction to Pattern in C

The First-Class ADT Pattern

The State Pattern

The Strategy Pattern

The Observer Pattern

The Reactor Pattern

Idiomatic Expressions

Conclusion

Implementing the Reactor Pattern - Part 1

The Reactor pattern