C# Online Compiler | .NET Fiddle

using System;
using System.Diagnostics;
					
public class Program
{
	public static void Main()
	{
		var foo = new Foo { Bar = new Bar { Baz = "Hello" } };
		var foo1 = new Foo();
		
		var i = foo._(_=>_.Bar)._(_=>_.Baz);			//equivalent to foo?.Bar?.Baz in C# 6		
		Console.WriteLine("i is '{0}'", i);				//should be 'Hello'
		
		var j = foo1._(_=>_.Bar)._(_=>_.Baz);			//equivalent to foo1?.Bar?.Baz in C# 6		
		Console.WriteLine("j is '{0}'",j);				//should be '' since j is null, but shouldn't throw exception either.
		
		Console.WriteLine("js is null? {0}", j == null);
		
		string s = null;		
		var x = s._(_=>_.Substring(0, 5));				//calling string method via null propagation.
		Console.WriteLine("x is '{0}'", x);

		var s1 = "Hello, World!";		
		var x1 = s1._(_=>_.Substring(0, 5));
		Console.WriteLine("x1 is '{0}'", x1);

		string s2 = default(string);
		Console.WriteLine("s2 is null? {0}", s2 == null);
		var x2 = s2._(_=>_.Trim());						//equivalent to s2?.Trim() in C# 6
		Console.WriteLine("x2 is '{0}'", x2);			//This is a bit misleading since default(string) is actually null which Console.WriteLine / String.Format happily parses to "" (to empty string).
		Console.WriteLine(x2._(_=>_.Trim()));			//Therefore you will need to guard x2 as well if you try to Trim or call any other String methods on it.
		
		try 
		{
			Console.WriteLine(x2.Trim());              //Otherwise it will blow up with NullReferenceException...
		}
		catch(Exception ex)
		{
			Console.WriteLine("Can't call x2.Trim()! Exception: {0}", ex);
		}
		
	}
}

public class Foo 
{
	public Bar Bar { get; set; }
}

public class Bar
{
	public string Baz { get; set; }
}

public static class ObjectExtension
{
	//Probably not a good idea to name your method _, but it's the shortest one I can find, I wish it could be _?, but can't :(
	public static K _<T, K>(this T o, Func<T, K> f) 
	{
		try 
		{
			var z = f(o);
			return z;			
		}
		catch(NullReferenceException nex) 
		{
			Trace.TraceError(nex.ToString());
			return default(K);
		}
		
	}
}

 
using System;
using System.Diagnostics;
                    
public class Program
{
    public static void Main()
    {
        var foo = new Foo { Bar = new Bar { Baz = "Hello" } };
        var foo1 = new Foo();
        
        var i = foo._(_=>_.Bar)._(_=>_.Baz);            //equivalent to foo?.Bar?.Baz in C# 6       
        Console.WriteLine("i is '{0}'", i);             //should be 'Hello'
        
        var j = foo1._(_=>_.Bar)._(_=>_.Baz);           //equivalent to foo1?.Bar?.Baz in C# 6      
        Console.WriteLine("j is '{0}'",j);              //should be '' since j is null, but shouldn't throw exception either.
        
        Console.WriteLine("js is null? {0}", j == null);
        
        string s = null;        
        var x = s._(_=>_.Substring(0, 5));              //calling string method via null propagation.
        Console.WriteLine("x is '{0}'", x);
​
        var s1 = "Hello, World!";       
        var x1 = s1._(_=>_.Substring(0, 5));

Cached Result

i is 'Hello'
j is ''
js is null? True
x is ''
x1 is 'Hello'
s2 is null? True
x2 is ''

Can't call x2.Trim()! Exception: System.NullReferenceException: Object reference not set to an instance of an object.
at Program.Main() in c:\Windows\Temp\vu1kpcs2.0.cs:line 35