Reference Lazy<T> implementation for Unity

Lazy.cs

using System;


public class Lazy<T> {
	public Lazy(Func<T> factory)
	{
		if (factory == null)
		{
			throw new ArgumentNullException("Lazy<T> doesn't accept null factory");
		}
		_factory = factory;
	}
	
	public T Value 
	{
		get
		{
			if (_factory != null)
			{
				_value = _factory();
				_factory = null;
			}
			return _value;
		}
	}
		
	
	public bool IsValueCreated { get { return _factory == null; } }
								
	private Func<T> _factory;
	private T _value;
}

public static class Program
{
	public static void Main()
	{
		var lazy = new Lazy<int>(() => new System.Random().Next(0, 100));
		Console.WriteLine("Initialized: " + lazy.IsValueCreated);
		var value = lazy.Value;
		Console.WriteLine("Initialized: " + lazy.IsValueCreated);
		Console.WriteLine("Value: " + lazy.Value + " == " + value);
		
	}
}