问题描述

我经常在 C++ 中使用的东西是让一个类 A 通过 A 处理另一个类 B 的状态进入和退出条件> 构造函数和析构函数，以确保如果该范围内的某些内容引发异常，则 B 在退出范围时将具有已知状态.就首字母缩略词而言，这并不是纯粹的 RAII，但它仍然是一种既定模式.

Something I often used back in C++ was letting a class A handle a state entry and exit condition for another class B, via the A constructor and destructor, to make sure that if something in that scope threw an exception, then B would have a known state when the scope was exited. This isn't pure RAII as far as the acronym goes, but it's an established pattern nevertheless.

在C#中，我经常想做的事

In C#, I often want to do

class FrobbleManager
{
    ...

    private void FiddleTheFrobble()
    {
        this.Frobble.Unlock();
        Foo();                  // Can throw
        this.Frobble.Fiddle();  // Can throw
        Bar();                  // Can throw
        this.Frobble.Lock();
    }
}

需要这样做

private void FiddleTheFrobble()
{
    this.Frobble.Unlock();

    try
    {            
        Foo();                  // Can throw
        this.Frobble.Fiddle();  // Can throw
        Bar();                  // Can throw
    }
    finally
    {
        this.Frobble.Lock();
    }
}

如果我想保证 FiddleTheFrobble 返回时的 Frobble 状态.代码会更好

if I want to guarantee the Frobble state when FiddleTheFrobble returns. The code would be nicer with

private void FiddleTheFrobble()
{
    using (var janitor = new FrobbleJanitor(this.Frobble))
    {            
        Foo();                  // Can throw
        this.Frobble.Fiddle();  // Can throw
        Bar();                  // Can throw
    }
}

FrobbleJanitor看起来大致像

class FrobbleJanitor : IDisposable
{
    private Frobble frobble;

    public FrobbleJanitor(Frobble frobble)
    {
        this.frobble = frobble;
        this.frobble.Unlock();
    }

    public void Dispose()
    {
        this.frobble.Lock();
    }
}

这就是我想要做的.现在现实赶上了，因为我 想要 使用 需要 FrobbleJanitor 使用 with using.我可以认为这是一个代码审查问题，但有些事情困扰着我.