[Serializable]
public class Lazy<T>
{
    public Lazy();
    public Lazy(bool isThreadSafe);
    public Lazy(Func<T> valueFactory);
    public Lazy(Func<T> valueFactory, bool isThreadSafe);

    public bool IsValueCreated { get; }
    public T Value { get; }

    public override string ToString();
}
注:VS2010 Beta2对Lazy<T>和VS2010 Beta1有较大差异,因此本文仅以最新版本为标准,并不保证最终.NET 4.0正式版的实际情况。