RaspberryIO/Unosquare.Swan.Lite/Abstractions/SingletonBase.cs
2019-02-17 14:08:57 +01:00

60 lines
1.9 KiB
C#

namespace Unosquare.Swan.Abstractions
{
using System;
/// <summary>
/// Represents a singleton pattern abstract class.
/// </summary>
/// <typeparam name="T">The type of class.</typeparam>
public abstract class SingletonBase<T> : IDisposable
where T : class
{
/// <summary>
/// The static, singleton instance reference.
/// </summary>
protected static readonly Lazy<T> LazyInstance = new Lazy<T>(
valueFactory: () => Activator.CreateInstance(typeof(T), true) as T,
isThreadSafe: true);
private bool _isDisposing; // To detect redundant calls
/// <summary>
/// Gets the instance that this singleton represents.
/// If the instance is null, it is constructed and assigned when this member is accessed.
/// </summary>
/// <value>
/// The instance.
/// </value>
public static T Instance => LazyInstance.Value;
/// <inheritdoc />
public void Dispose() => Dispose(true);
/// <summary>
/// Releases unmanaged and - optionally - managed resources.
/// Call the GC.SuppressFinalize if you override this method and use
/// a non-default class finalizer (destructor).
/// </summary>
/// <param name="disposeManaged"><c>true</c> to release both managed and unmanaged resources; <c>false</c> to release only unmanaged resources.</param>
protected virtual void Dispose(bool disposeManaged)
{
if (_isDisposing) return;
_isDisposing = true;
// free managed resources
if (LazyInstance == null) return;
try
{
var disposableInstance = LazyInstance.Value as IDisposable;
disposableInstance?.Dispose();
}
catch
{
// swallow
}
}
}
}