try...finally的妙用

受博文 C#中Finally的一個不太常見的用法 的啟發，正好在開發中遇到這樣一段代碼：

public bool ChangeBlogApp(Guid userID, string oldBlogApp, string newBlogApp)
{
    CacheFactory.Default.Remove(CacheKeyManager.GetBlogConfigCacheKey(oldBlogApp));
    CacheFactory.Default.Remove(CacheKeyManager.GetBlogConfigCacheKey(newBlogApp));
    return _bcProvider.UpdateBlogApp(userID, newBlogApp);
}

需要把2行CacheFactory.Default.Remove的代碼移至_bcProvider.UpdateBlogApp之后。

按照以前的做法，代碼會改成這樣（增加一個局部變量）：

public bool ChangeBlogApp(Guid userID, string oldBlogApp, string newBlogApp)
{
    var result = _bcProvider.UpdateBlogApp(userID, newBlogApp);
    CacheFactory.Default.Remove(CacheKeyManager.GetBlogConfigCacheKey(oldBlogApp));
    CacheFactory.Default.Remove(CacheKeyManager.GetBlogConfigCacheKey(newBlogApp));
    return result;
}

而使用try...finally，可以無需增加局部變量，代碼如下：

public bool ChangeBlogApp(Guid userID, string oldBlogApp, string newBlogApp)
{
    try
    {
        return _bcProvider.UpdateBlogApp(userID, newBlogApp);
    }
    finally
    {
        CacheFactory.Default.Remove(CacheKeyManager.GetBlogConfigCacheKey(oldBlogApp));
        CacheFactory.Default.Remove(CacheKeyManager.GetBlogConfigCacheKey(newBlogApp));
    }
}