Ruby was the impetus for me to write a Guard clause that automatically get a parameter name from code. What do I mean by that? This passes:

[Test]
public void Expression_guard_can_get_parameter_name_from_expression()
{
	object address = null;
	Assert.Throws<ArgumentException>(() => Guard.AgainstNull(() => address),
		"The parameter address must not be null");
}

Notice how I didn’t specify the string “address” anywhere, the Guard.AgainstNull method got it from the expression () => address. I’m sure I’ve used constructs like this in C# before, but I haven’t written any yet. I wonder in what other ways I can abuse Expressions?

The implementation, that is not well tested by any means:

public static void AgainstNull<T>(Expression<Func<T>> expression)
{
	AgainstNull(expression, "expression");

	string paramName = "";
	var memberExpression = expression.Body as MemberExpression;
	if (memberExpression != null)
	{
		paramName = memberExpression.Member.Name;
	}
	T instance = expression.Compile().Invoke();
	AgainstNull(instance, paramName);
}