Playing with C# 6 and 7

My projects at work are stuck on older versions of C#, so whilst reading C# 7.0 in a Nutshell by Ben Albahari and Joseph Albahari, I thought I would try out some of the new features I’ve been missing out on.

We’ll start with C# 6’s read-only automatic properties.

C# 6

Read only auto properties

Immutability provide benefits such as:

• thread safety
• reduces cognitive load
• easy to test

Prior to C# 6 we could nearly achieve immutability with automatic properties by using a private set as in the code below, though we lose immutability if someone else adds in a method such as MofifyFoo(bool newFoo) to our class as this will have access to our IsFoo property:

public class FooChecker
{
  public bool IsFoo { get; private set; }
  
  public FooChecker(bool isFoo)
  {
    IsFoo = isFoo;
  }

  public void ModifyFoo(bool newFoo)
  {
    IsFoo = newFoo;
  }
}

To achieve actual immutability prior to C# 6 we would have to be a bit more verbose and include a readonly backing field.

public class FooChecker
{
  public bool IsFoo { get { return _isFoo; } }
  private readonly bool _isFoo;

  public FooChecker(bool isFoo)
  {
    _isFoo = isFoo;
  }
  
  public void ModifyFoo(bool newFoo)
  {
    IsFoo = newFoo; // this will not compile
  }
}

Now we no longer need to worry anybody changing the value of IsFoo.

C# 6 enables us to do away with verbosity with the following code:

public class FooChecker
{
  public bool IsFoo { get; }

  public FooChecker(bool isFoo) 
  {
    IsFoo = isFoo;
  }

  public void ModifyFoo(bool newFoo)
  {
    IsFoo = newFoo; // this will not compile
  }
}