如果我总是用TryGetValue访问.NET字典？ [英] Should I always use TryGetValue to access .net Dictionaries?

问题描述

在<一个href="http://stackoverflow.com/questions/886814/why-doesnt-net-provide-us-with-the-key-when-it-raises-a-keynotfound-exception">another SO问题，我见过几个人建议我总是使用TryGetValue。

In another SO question, I've seen several people recommend me to always use TryGetValue.

虽然我总是用TryGetValue在包含？/访问模式，我避免在目的这个模式时，我希望的关键，始终处于字典。然后，我去一个直接索引器访问，让就抛出一个异常，如果该键不存在，因为意想不到的事情真的发生了（即重点不是在字典中，而我希望它）。

While I always use TryGetValue over the Contains?/Access pattern, I avoid this pattern on purpose when I expect the key to always be in the dictionary. I then go for a direct indexer access, so that an exception is raised if the key isn't there, because something unexpected really happened (i.e. the key wasn't in the dictionary while I expect it to).

由于好像是对我的最佳实践一个普遍的共识（四分之三的人对我所提到的明确建议使用TryGetValue在所有的时间后），我渴望去阅读上的进一步讨论话题...

Since there seems to be a general consensus against my "best-practice" (3 out of 4 people on the post I mentioned explicitly advised to use TryGetValue at all time), I'm eager to read an extended discussion on that topic...

推荐答案

没有，你是完全正确IMO。

No, you're entirely right IMO.

有这样做没有意义的：

if (dict.TryGetValue(key, out value))
{
    // whatever
}
else
{
    throw new SomeException("key '" + key + "' wasn't in dictionary");
}

的唯一好处，超过：

The only benefit of that over:

value = dict[key];

是，你得到一个更加明确的异常消息......但是可读性的成本，海事组织。

is that you get a more explicit exception message... but at the cost of readability, IMO.

这就像铸造VS使用为 - 异常是一个正确的结果，当状态是错误的，所以用它给出的行为形式

It's like casting vs using as - an exception is the right result when the state is "wrong", so use the form which gives that behaviour.

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