Is there such a thing as a chained NULL check?

Question

I have the following ugly code:

if (msg == null || 
    msg.Content == null || 
    msg.Content.AccountMarketMessage == null || 
    msg.Content.AccountMarke         


        

Answer 1

You can lazily evaluate the values using lambda expressions. This is overkill for a simple null check, but can be useful for chaining more complex expressions in a "fluent" manner.

Example

// a type that has many descendents
var nested = new Nested();

// setup an evaluation chain
var isNull =
    NullCheck.Check( () => nested )
        .ThenCheck( () => nested.Child )
        .ThenCheck( () => nested.Child.Child )
        .ThenCheck( () => nested.Child.Child.Child )
        .ThenCheck( () => nested.Child.Child.Child.Child );

// handle the results
Console.WriteLine( isNull.IsNull ? "null" : "not null" );

Code

_{This is a full example (albeit draft-quality code) that can be pasted into a console app or LINQPad.}

public class Nested
{
  public Nested Child
  {
      get;
      set;
  }
}

public class NullCheck
{
   public bool IsNull { get; private set; }

   // continues the chain
   public NullCheck ThenCheck( Func