使用终于赶上来代替 [英] Using finally instead of catch

问题描述

我已经看到了这种模式，现在几次：

I've seen this pattern a few times now:

        bool success = false;
        try
        {
            DoSomething();
            success = true;
        }
        finally
        {
            if (!success)
                Rollback();
        }

和我一直在想：为什么这更好的比使用捕回退？

And I've been wondering: Why is this better than using catch for rollbacks?

        try
        {
            DoSomething();
        }
        catch
        {
            Rollback();
            throw;
        }

什么是确保变化的两种方法之间的差异被回滚上失败？

What are the differences between the two ways of making sure changes are rolled back on failure?

推荐答案

这里的明确目标是使还原是叫任何错误的情况。这两个代码片段实现这一目标。第一次使用了最后，这始终运行，这验证尝试块的最后一行顺利抵达。第二捕获任何错误，回滚事务，然后重新抛出被捕捉到的异常。无论是代码片段的结果是，抛出的异常将导致回滚，同时仍然向上冒泡到一个新的水平。

The clear goal here is to cause Rollback to be called in the event of any error. Both code snippets accomplish this goal. The first uses a finally, which always runs, that verifies that the last line of the try block was successfully reached. The second catches any errors, rolls back the transaction, and then re-throws the exception that was caught. The result of either snippet is that any exceptions thrown will result in a rollback while still bubbling up to the next level.

您提到，该项目从Java移植。在Java中，您可以 重新抛出异常相似你如何在C＃中使用扔; 。您也可以抛出一个新的异常将依然保持调用堆栈（ET人）。第二个是一个位更清晰/ C＃中简单（不以大量尽管）和第一有在Java中实际工作作为写入的优点。

You mentioned that the project was ported from Java. In Java, you can re-throw an exception similarly to how you can in C# using throw;. You can also throw a new exception that will still maintain the call stack (et al). The second is a bit clearer/simpler in C# (not by a lot though) and the first has the advantage of actually working in Java as written.

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