BOOK REVIEW – EFFECTIVE PROGRAMMING MORE THAN WRITING CODE BY JEFF ATWOOD

coverofJeffAtwood

Jeff Atwood is somewhat of a celebrity in software development and programming circles, he along with Joel Spolsky are the founders of StackOverflow.com, a question and answer website all programmers and software engineers must be familiar with.

The book, initially published in 2012, is constructed from posts on Jeff Atwood’s blog, CodingHorror.com. The posts are sorted into different sections based on an overall theme, for example, hiring programmers, workspace setup, code testing, etc. Thus, making for a coherent and flowing reading experience.  This is where the value of this book opposed to reading all these posts on his blog for free comes in, a more convenient reading experience.

Effective Programming More than Writing Code is one of the best and one of my favorite books on the topic of software development, it is a must-read for anyone who is a professional software developer, and personally, I have read through it numerous times over the years. The book is an easy, quick read and a vast amount of great ideas and concepts are communicated that will keep you thinking long after you have stopped reading.

There are however a few problems with this book, firstly in the print version there are quite a few printing errors where the top line of the page is cut off, this is present on 2 pages in my copy. This is not a problem in the electronic version available on the Kindle store.

Secondly, as this book was constructed from blog posts, numerous hyperlinks and embedded videos are present, which obviously do not work in a printed format. This is, however, more of an annoyance than a problem as this does not hinder the concept being communicated.

Even given these problems, I would still highly recommend this book. So, if you work in or are interested in software development, pick it up.

BOOK REVIEW – EFFECTIVE PROGRAMMING MORE THAN WRITING CODE BY JEFF ATWOOD

The Dark Art of DevOps (and how Azure DevOps fits in)

Here is a Post n wrote for my Companies blog, originally posted here.

DevOps has become a hot topic in organisations over the past year or so. However, there seems to be a lot of confusion regarding what DevOps actually entails. So, what is DevOps?

If you asked a more sales-inclined individual, you may get a response along the lines of: DevOps digitally transforms an organisation’s development department by bridging the gap between development and operations, resulting in higher quality solutions, fewer bugs, quicker delivery times, shorter recovery times, and controlling scope creep.”

This sounds amazing! However, it does not answer the question as to what DevOps really is. So, I will be taking a different approach to delve into what DevOps entails.

DevOps is based on the principal of continuous improvements in the Software Development Lifecycle, and consists of principles, practices and tools that allow an organisation’s development department to deliver projects at a high velocity, while maintaining quality and continuously improving the process associated with delivery. This is where Azure DevOps comes in. Azure DevOps is a selection of tools that facilitate the implementation of DevOps within an organisation.

DevOps consists of five main pillars (which are supported by processes, practices and tools), namely:

1. Plan and Track

This involves planning what development work needs to be completed and tracking progress against that. The tool Azure DevOps offers here is Azure Boards.

2. Develop

This is where your software developers write code and store that code. In the Azure DevOps ecosystem, the tools that used here are Visual Studio, Visual Studio Code and Azure Repos as a source code repository.

3. Build and Test

Automated builds and testing are a very important part of DevOps, as this automation frees up valuable resource time to focus on more imperative tasks. Automated builds can be set up to trigger new builds (compiling source code into executable programs) based on certain criteria (for example, “once a day”), and automated tests can then be run to verify that everything is working as expected without the intervention of a person.  Azure Pipelines and Azure Test Plans are the tools utilized here.

4. Deploy

The next step is Automated Deploy – first to a UAT\Test environment and eventually to production. Doing deploys in this manner prevents unwanted changes being accidentally deployed from a developer’s machine and introduces additional controls to only deploy what is wanted and limiting the introduction of problems.  By automating the deployment of systems deployment times are also drastically reduced and thus system down time is reduced. Azure Release Management is the Azure DevOps tool used to automate deployments.

5. Monitor and Operate

After a system has been deployed, it needs to be monitored and operational activities need to be performed to ensure it is up and running and running optimally. Azure Monitor and Application Insights are the tools available in the Azure DevOps tool-belt for this.

With the tools provided by Microsoft Azure DevOps, as well as industry tried and tested principles, the above five pillars can dramatically improve the operations and output of a development department while driving down operational costs.

Now that we understand what DevOps is and how it works, what outcomes can we expect from mastering the 5 pillars?

  • Better quality solutions
  • Quicker delivery times
  • Fewer bugs
  • Shorter recovery times to resolve bugs
  • Prevents uncontrolled scope creep
  • Improved collaboration and agility in teams
  • Better cross-skilling in teams
  • More automation
The Dark Art of DevOps (and how Azure DevOps fits in)

BITE SIZE C# – LINQ

LINQ or Language Integrated Query is part of the Microsoft .NET Framework and it adds native data querying capabilities to .NET languages.

LINQ allows the user to query:

  • Objects in Memory (i.e. collections such as lists) using LINQ to Objects
  • Databases using LINQ to Entities
  • XML using LINQ to XML
  • ADO.Net Datasets using LINQ to Datasets

LINQ can either be implemented using predefined extension methods or alternatively using LINQ Query Operators.

Below are three examples utilising LINQ Extension methods:

In this example a list of Book objects is filtered to return only the Objects where the price is less than 10.

List<Book> cheapBooks = books.Where(b=>b.Price < 10);

 

In this example a list of Book objects is filtered to return only the Objects where the price is less than 10 and additionally the newly created list of Book objects is sorted alphabetically based on the Title field.

List<Book> cheapBooks = books.Where(b=>b.Price < 10).OrderBy(b.Title);

 

In this example the cheapBooks list is filtered to only return the Titles of the books therein and these Titles are then inserted into a new list of strings.

List<string> cheapBooksTitles = cheapBooks.Select(b=>b.Title);

 

Multiple extension methods can be combined to ascertain the desired results, for example:

List<string> cheapBooksTitles = books.Where(b=>b.Price).OrderBy(b.Title);
                                   .Select(b=>b.Title);

 

LINQ query operators tend to be slightly more verbose, and the above example can be implemented with query operators as follows:

List<string> cheapBooksTitles = from b in books
                         where b.Price < 10
                         orderby b.Title
                         select b.Title;

 

Some common extension methods are:

Single

var book = books.Single(b=>b.Title == ”Building Robots”);

Returns a single object that matches the defined criteria. However note that in the event that none or more than one book matches the criteria specified an exception will be thrown.

 

SingleOrDefault

var book = books.SingleOrDefault(b=>b.Title == ”Building Robots”);

Returns a single object that matches the defined criteria, if more than one book matches the criteria specified an exception will be thrown, however if no books match the criteria the default value defined will be returned.

 

First

Returns the first object that matches the criteria, however if no matches are found an exception is thrown.

 

FirstOrDefault

Returns the first object that matches the criteria and if no match is found the default value will be returned.

 

Last

Returns the last object that matches the criteria, however if no matches are found an exception is thrown.

 

LastOrDefault

Returns the last object that matches the criteria and if no match is found the default value will be returned.

 

Max

var maxValue = books.Max(b=>b.Price);

Max is used with numeric values and will return the highest value that is contained in the Price field in the Book objects.

 

Min

var minValue = books.Min(b=>b.Price);

Min is another operation used with numeric values and will return the smallest value that is contained in the Price field in the Book objects.

 

Sum

var totalPrice = books.Sum(b=>b.Price);

Sum is used to add up all the values in a numeric field.

 

There are many other methods available to filter and manipulate data in LINQ and the possibilities for the utilisation of LINQ are nearly endless, for example

var bookSelection = books.Skip(2).Take(3);

The above example will skip the first two books in the books list and take the next three placing them into the newly created bookSelection list.

The best option to gain a better insight of what is possible with LINQ is to give it a try.

BITE SIZE C# – LINQ

BITE SIZE C# – LAMBDA EXPRESSIONS

A lambda expression is a function definition with no name, no access modifier and no return statement. Lambda expressions are also known as Anonymous methods or functions.

The syntax for the definition of a lambda expressions is as follows:

(arguments) => expression

The below C# code does not use lambda expressions and is given as a comparative reference point:

static int SquareNumber(int number)
{
   return number*number;
}

static void Main(string[] args)
{
   Int y = SquareNumber(10);
   Console.WriteLine(y); // This will display 100
}

The above code can be refactored using a lambda expression as follows:

static void Main(string[] args)
{

   Func<int,int> square = number=>number*number;
   Console.WriteLine(square(10)); // This will display 100

}

The result of this refactor is fewer lines of code in order to achieve the same result.

Lambda expressions can also make use of Delegates as shows here:

delegate int squareDelegate (int number);

static void Main(string[] args)
{
   squareDelegate square = number=>number*number;
   Console.WriteLine(square(10)); // This will display 100
}

 

The syntax for a lambda expression that takes no arguments is as follows:

()=>expression

For one argument:

X=>expression

For more than one argument:

(x,y,z)=>expression

 

Lambda expressions can also be very effectively used with objects that implement the IEnumerable and IQueryable interfaces to filter or search based on defined criteria, for example:

var highPriceList = PriceList.FindAll(a=>a.Price>10);

This will return all items with a price larger than 10, and place these items in the highPriceList.

 

var nyCustomers = Customers.Where(a=>a.City==”New York”);

This will place all customers with the city property set to “New York” into the nyCustomers collections.

Lambda expressions are an extremely useful tool with many other uses.

BITE SIZE C# – LAMBDA EXPRESSIONS

Bite Size C# – Eventing\Observer Pattern

Let us have a look at the eventing or observer pattern. This pattern is based on the raising and handling of events. Events are a mechanism for the communication between object that allow us to build loosely coupled applications that can be easily extended.

At a high level this pattern functions as follows:
An object (known as the Publisher) defines a contract (delegate method) to which other objects (knows as Subscribers) must comply in order to be notified of a certain condition occurring in the Publisher object. This is achieved as follows, when a certain state is reached in the Publisher object an event will be raised, which will then trigger all the Subscriber objects to react by executing the method defined within the individual Subscriber objects that matches the delegate method as defined in the Publisher.

Now let us have a look at an example:

First let us create the Publisher, here we have to do three things:
1. Define a delegate which will act as the contract between the Publisher and Subscribers.
2. Define an event based on the delegate.
3. Raise the defined event.

public class KillerRobotPublisher
{
	public delegate void KillerRobotEventHandler(object source, EventArgs args);

	public event KillerRobotEventHandler KillerRobotAction;

	protected virtual void OnKillerRobotAction()
	 {
		if(KillerRobotAction!=null) //check if there are any subscribers
			{
				KillerRobotAction(this,EventArgs.Empty);
			}
	 }

	public void DoKillerRobotAction(string action)
	 {
		Console.WriteLine(“Killer Robot is doing “ +action);
		//add additional action logic here

		OnKillerRobotAction();
	}
}

Next let us create a Subscriber to subscribe to the KillerRobotAction event on the Publisher.

public class KillerRobotSubscriber
{
	public void OnKillerRobotAction(object source, EventArgs args)
     //this method conforms to the delegate defined in the Publisher
	 {
		Console.WriteLine(“The Killer Robot did something!”);
	 }
}

Now lastly let us create a basic application to instantiate the objects and to subscribe the Subscriber to the Publisher:

class Program
{
	static void Main(string[] args)
	{
		var killerRobotPub = new KillerRobotPublisher(); //Instantiate Publisher Object
		var killerRobotSub = new KillerRobotSubscriber(); //Instantiate Subscriber Object 

		killerRobotPub.KillerRobotAction += killerRobotSub.OnKillerRobotAction;
		//Subscribe the KillerRobotSubscriber to the KillerRobotAction event on the KillerRobotPublisher.

		killerRobotPub.DoKillerRobotAction(“A Dance”);
	}
}

The console output of this application will look like this:

console_Output

Bite Size C# – Eventing\Observer Pattern

Bite Size C# – Extension Methods

Extension methods allow us to add methods to existing classes without changing the class’ source code, nor by inheriting from the class. Extension methods are more relevant when wanting to add a method to a class from which one cannot inherit, such as sealed classes.
Just note, you cannot use extension methods with a static class as extension methods require an instance variable for an object in order to be utilised.
Let us look at an example, here we will add an extension method to the string class, which is a sealed class (i.e. you cannot inherit from this class).

class Program
{
	static void Main(string[] args)
	{
		string sentence=  “This is something a person would say.”;

		var robotSentence = sentence.ToRobot();
		Console.WriteLine(robotSentence);
	}
}

public static class StringExtensions
{
	public static string ToRobot(this string str)
	{
		if(String.IsNullOrEmpty(str)) return str;
		var words = str.Split(‘ ‘);
		var robotStr = String.Empty;

		foreach(var word in words)
		{
			if(word.Length > 4)
			{
				robotStr+=“BEEP “;
			} else {
				robotStr+=“BOOP ”;
			}
		}

		return robotStr.Trim();
	}
}

Also note that extension methods must be non-generic static methods defined in a static class.

Bite Size C# – Extension Methods

Bite Size C# – Delegates

A delegate is a form of a type-safe function pointer. More simply put, it is an object that knows how to call a method, i.e. a reference to a method. Delegates are useful as they assist us in writing flexible and extendable applications.

Delegates are useful when using the eventing design pattern also known as the observer pattern. The eventing or observer pattern consists of an object, called the subject or publisher, which maintains a list of dependent objects, called observers or subscribers, and notifies them automatically of a state change in the subject-object by raising an event and then calling a method on the observer objects by using a delegate. We will cover this pattern in more detail when I cover events in a separate post.

For now, let us simply focus on delegates.

So, let us look at an example:


public class KillerRobot
{
	public string Name { get; set; }
}

public class KillerRobotActuator
{
	public delegate void KillerRobotActionHandler(KillerRobot robot); 	//Declare delegate which will act as a
															//signature for methods that can be
															//referenced.

	public void DoAction(string robotName, KillerRobotActionHandler actionHandler)
	{
		var robot = new KillerRobot {Name = robotName	};
		actionHandler(robot);
	}
}

public class RobotActions
{
	public void RobotTalk(KillerRobot robot)
	{
		Console.WriteLine(“{0} is Talking.”, robot.Name);
	}

	public void RobotDance(KillerRobot robot)
	{
		Console.WriteLine(“{0} is Dancing.”, robot.Name);
	}
}

class Program
{
	static void Main(string[] args)
	{
		var robotActuator = new KillerRobotActuator();
		var robotActions = new RobotActions();
		KillerRobotActuator.KillerRobotActionHandler actionHandler = robotActions.RobotTalk;
		actionHandler += robotActions.RobotDance;
		actionHandler += RobotPowerOff;

		robotActuator.DoAction(“The Geek”,actionHandler);
	}

	static void RobotPowerOff(KillerRobot robot)
	{
		Console.WriteLine(“{0} has turned off.”, robot.Name);
	}
}

So, in this basic example we have a class KillerRobotActuator which declares a delegate:

public delegate void KillerRobotActionHandler(KillerRobot robot);

Any method that complies to this signature can then be added to this delegate and in the DoAction method where the following is executed:

actionHandler(robot);

All the methods that have been added to the actionHandler will then be executed.
We can see in the Main method of the Program class that a new KillerRobotActionHandler is declared and three method references are added to it as below:

KillerRobotActuator.KillerRobotActionHandler actionHandler = robotActions.RobotTalk;
actionHandler += robotActions.RobotDance;
actionHandler += RobotPowerOff;

And then finally the DoAction method on KillerRobotActuator is executed, passing in the above declared actionHandler containing references to the three methods:

robotActuator.DoAction(“The Geek”,actionHandler);

All three the methods that are referenced by the actionHandler comply to the signature defined in the delegate declaration in the KillerRobotActuator class. i.e. a void return type and an input parameter of type KillerRobot.
It is also worth mentioning that of the methods referenced, two are contained in a separate class RobotActions and the third is a static method declared in the Program class, so methods from multiple different class locations can be added as long as they comply to the signature of the delegate declares.

 

Bite Size C# – Delegates