Can I force my own short-circuiting in a method call?

Question

Suppose I want to check a bunch of objects to make sure none is null:

if (obj != null &&
    obj.Parameters != null &&
    obj.Parameters.UserSet         


        

Answer 1

You could use reflections if you don't mind losing static type safety. I do mind, so I just use your first short-circuiting construction. A feature like Eric mentioned would be welcome :)

I've thought about this problem a few times. Lisp has macros that solve the problem in the way you mentioned, since they allow you to customize your evaluation.

I have also tried using extension methods to solve this problem, but nothing there is less ugly than the original code.

Edit: (Replies don't let me insert code blocks, so editing my post)

Oops, didn't keep up on this. Sorry about that :)

You can use reflections to look up and evaluate a member or property via a string. A class one of my friends wrote took a syntax like:

new ReflectionHelper(obj)["Parameters"]["UserSettings"]

It worked via method chaining, returning a ReflectionHelper at each level. I know that NullReferenceException is a problem in that example. I just wanted to demonstrate how evaluation can be deferred to runtime.

An example slightly closer to being helpful:

public class Something
{
  public static object ResultOrDefault(object baseObject, params string[] chainedFields)
  {
    // ...
  }
}

Again, this syntax stinks. But this demonstrates using strings + reflections to defer evaluation to runtime.