Lambda Simplified

Introduction

Lambda expressions in C# are simple to use, but when you see Lambda expression for the first time, it will be so confusing. The article simplifies the understanding of a Lambda expression by taking you through a code evolution tour.

Evolution

In a typical .NET 1.0 code, the simple event handler can be written as follows:

public Form1()
{
   InitializeComponent();
   this.button1.Click += new System.EventHandler(this.button1_Click);
}

private void button1_Click(object sender, EventArgs e)
{
   MessageBox.Show("Hello Events");
}

By using .NET 2.0 Anonymous method, we can simplify the code by:

• Removing method name
• Bringing it closer to event handler (move the code within the {})
• No need to add Event Handler. You can use Delegate keyword to create a delegate object of the anonymous method.

public Form1()
{
   InitializeComponent();
   this.button1.Click += new System.EventHandler(this.button1_Click);

    private void button1_Click delegate (object sender, EventArgs e)
    {
        MessageBox.Show("Hello Events");
    }
}

So if you use anonymous method, the code looks like:

public Form1()
{
   InitializeComponent();
   this.button1.Click += delegate (object sender, EventArgs e)
                         {
                             MessageBox.Show("Hello Events");
                         };
}

By using .NET 3.0 lambda syntax, the code is even more simplified.

• You can remove delegate keyword
• No need to explicitly state the param types, as the compiler can inference type types
• When we have single expression, no need for {} also.
• and introduce => to split the param and method expression.

public Form1()
{
   InitializeComponent();
   this.button1.Click += delegate (object sender, EventArgs e) =>
                         {
                             MessageBox.Show("Hello Events");
                         };
}

So now with Lambda syntax, the same code simplified as below:

public Form1()
{
   InitializeComponent();
   this.button1.Click += (sender, e) => MessageBox.Show("Hello Events");
 }

Conclusion

The article try to simplify the understanding of Lambda expression. To know more about Lambda, check this MSDN article.