using System;
using Chernobyl.Event;
using Chernobyl.Values;

namespace Chernobyl.Readiness
{
    /// <summary>
    /// An interface for working with objects that have to be "readied" or 
    /// become available before they can be used reliably. If code queries 
    /// information from an object that is not ready, the query may result in a 
    /// default value being returned or an exception being thrown (it is 
    /// recommended that implementors use the <see cref="NotReadyException"/> 
    /// for this purpose). Resources that need to be loaded are examples of 
    /// objects that need to be readied before they can be used.
    /// </summary>
    public interface IReadyable
    {
        /// <summary>
        /// True if this instance has been readied, false if otherwise.
        /// </summary>
        bool IsReady { get; }

        /// <summary>
        /// An event that is raised right after this <see cref="IReadyable"/> 
        /// has been readied. If an event handler is added to this event 
        /// after it has become ready, then that event handler will be 
        /// invoked immediately.
        /// </summary>
        event EventHandler BecameReady;
    }
}