Lazy<T> .NET 3.5

On a large enterprise applicaiton I work on we are currently unable to upgrade from .NET3.5 to .NET4.0, although there is plenty of situations where we could use the .Lazy<T> class. So in order to get us through until we upgrade to .NET I have implemented a very basic .NET 3.5 version which can easily be replaced with the Microsoft version at a later date.

/// <summary>
/// A pre-.NET4 Lazy<T> implementation
/// </summary>
public class LazyLoader<T>
 where T : class
{
 private readonly object padlock;
 private readonly Func<T> function;

 private bool hasRun;
 private T instance;

 public LazyLoader(Func<T> function)
 {
  this.hasRun = false;
  this.padlock = new object();
  this.function = function;
 }

 public T Value()
 {
  lock (padlock)
  {
   if (!hasRun)
   {
    instance = function.Invoke();

    hasRun = true;
   }
  }

  return instance;
 }
}