# Friday, 30 April 2010

I began reading Agile Principles, Patterns and Practices in C# by Robert C Martin and Micah Martin after a friend recommended the chapters on pair programming.  My friend was right, of course. The Martins not only decribed pair programming but included an entertaining script of two developers pairing on a programming problem.

But, as I dove deeper into this book, I found a wealth of other information.

The book begins with a section on agile development, defining some basic terms and concepts recommended practices. It follows with a detailed section on good design practice. This second section is the most interesting, as it describes the famous SOLID principles. SOLID is an acronym for a set of good design practices:

S=Single Responsibility Principle: Each class should serve only one purpose and have only one reason to change.
O=Open-Close Principle: Classes should be open for extension but closed for modification
L=Liskov Substitution Principle: It should always be possible to substitute a derived class with its base class
I=Interface Segregation Principle: Interfaces implemented by a class are defined by the client objects that use that class; a class should implement a separate interface for each client that calls it.
D=Dependency Inversion Principle: To maintain flexibility, you should write code that depends on abstractions, such as interfaces.

Next, the authors present an overview of Unified Markup Language (UML), a graphical language used to describe software designs and requirements. Common UML diagrams and shapes are described and the author offers opinions of which ones are most useful and when to best use them.

The last half of the book is a case study of a Payroll System in which the authors use examples to illustrate the concepts introduced in the first half of the book.

Although C# is included in the title, the book does not focus on C# and almost none of the concepts are specific to any particular language. All the code examples are in C#, which makes it a bit more accessible if that is your strongest language.

The book is filled with lots of information and good advice. For example, the authors recommend an iterative approach to writing software, a test-first approach to development and encourage developers to refactoring their code frequently.

Whether you read all of Agile Principles, Patterns and Practices in C# or pick through the sections of interest, you will benefit from this book.