Question

Is there a better/shorter way to handle (lots of) null references, for example when I’m using LinqToXML.

I wrote this extention for XElement that handles it quite nicely, but maybe there is another way?

And what about the function name? ‘And’ isn’t really descriptive.

public static class XmlExtentions {     public static T And<T>(this T obj, Func<T, T> action) where T : XElement     {         return obj == null ? obj : action(obj);     } }  internal class Program {     private static void Main()     {         //create example xml element         var x =            XElement.Parse('<root><find><name>my-name</name></find></root>');          //old way         var test1 = x.Element('find');         if (test1 != null) test1 = test1.Element('name');         Console.WriteLine(test1);          //using the extentions method         var test2 = x.Element('find').And(findme => findme.Element('name'));         Console.WriteLine(test2);          Console.ReadLine();     } } 

PS: I know I could use XPath for this example, but that’s not always the case in more complex cases.

Answer 1

The overall approach is reasonable – although I’m not sure about the Func<T,T> which seems a bit restrictive. If you are limiting to returning the same thing, I wonder if just accepting the name (string) as the second arg wouldn’t be easier?

Re naming – perhaps borrow from LINQ? This is essentaially a Select – how about SelectOrDefault:

public static TResult SelectOrDefault<TSource, TResult>(     this TSource obj, Func<TSource, TResult> selector) where TSource : class {     return SelectOrDefault<TSource, TResult>(         obj, selector, default(TResult)); }  public static TResult SelectOrDefault<TSource, TResult>(     this TSource obj, Func<TSource, TResult> selector,     TResult @default) where TSource : class {     return obj == null ? @default : selector(obj); } 

(edit) maybe with the additional XElement specific:

public static XElement SelectOrDefault(     this XElement element, XName name) {     return element == null ? null : element.Element(name); }