c# - 采用 IDisposable 模式

Question

好的，我已经阅读了一些关于 IDisposable 最佳实践的文章，我想我基本上明白了(终于)。

我的问题与从 IDisposable 基类继承有关。我看到的所有示例都在子类中一遍又一遍地编写相同的代码块，但我看不出有什么好处。

为什么不简单地将一个虚方法放入基类中，在适当的时间从(私有(private)实现的)IDisposable 例程中调用它，这样子类就不会那么困惑，但仍然有机会做管理他们的资源？

我建议的基类:

public abstract class DreamDisposableBase : IDisposable
{
    private bool _disposed = false;


    protected virtual void LocalDispose(bool disposing)
    {   
    }

    ~DreamDisposableBase()
    { 
        // finalizer being called implies two things:
        //  1. our dispose wasn't called (because we suppress it therein)
        //  2. we don't need to worry about managed resources; they're also subject to finalization

        // so....we need to call dispose with false, meaning dispose but only worry about *unmanaged* resources:

        dispose(false);
    }


    void IDisposable.Dispose()
    {
        dispose(true);  // true argument really just means that we're invoking it explicitly
    }


    private void dispose(bool disposing)
    {
        if (!_disposed)
        {
            // give sub-classes their chance to release their resources synchronously
            LocalDispose(disposing);

            if (disposing)
            { 
                // true path is our cue to release our private heap variables...
            }

            // do stuff outside of the conditional path which *always* needs to be done - release  unmanaged resources

            // tell .net framework we're done, don't bother with our finalizer - 
            GC.SuppressFinalize(this);

            // don't come back through here
            _disposed = true;
        }
    }

}

Answer 1

我不希望每个类型都有终结器。很少需要在终结器中执行任何工作。如果 disposing 为真，几乎所有的实现都不会做任何事情。终结器会影响性能，因为它们会导致升级到 Gen2，需要清理两个集合并且调用终结器是单线程的。

大多数类不包装非托管资源，如果它们包装它们，则它们应该使用 SafeHandle 类型或其他类型。这也使得终结器变得不必要了。