blocks|key|1399592|text|Eric+Lippert在这方面有一个很好的article。如果你不想读整篇文章，答案是:返回接口。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1399593|entityMap|0|LINK|mutability|MUTABLE|url|http://blogs.msdn.com/ericlippert/archive/2008/09/22/arrays-considered-somewhat-harmful.aspx^0|M|7|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

Eric Lippert has a good <a href="http://blogs.msdn.com/ericlippert/archive/2008/09/22/arrays-considered-somewhat-harmful.aspx" rel="noreferrer">article</a> on this. In case you can't be bothered to read the entire article, the answer is: return the interface.

blocks|key|1400112|text|使用yield+return返回IEnumerable<T>。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1400113|entityMap|0|LINK|mutability|MUTABLE|url|http://msdn.microsoft.com/en-us/library/9k7k7cf0.aspx^0|2|C|G|E|2|C|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@$9|O|A|P|B|C]|$9|Q|A|R|B|C]]|D|@$9|S|A|T|1|U]]|E|$]]|$1|F|3|-4|5|6|7|V|8|@]|D|@]|E|$]]]|G|$H|$5|I|J|K|E|$L|M]]]]

Return an <code>IEnumerable&lt;T&gt;</code> using a <a href="http://msdn.microsoft.com/en-us/library/9k7k7cf0.aspx" rel="nofollow noreferrer"><code>yield return</code></a>.

blocks|key|1399875|text|如果返回的集合是只读的，这意味着您永远不希望更改集合中的元素，则使用IEnumerable<T>。这是不可变(至少从枚举本身的角度来看)元素的只读序列的最基本表示。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1399876|如果您希望它是一个可以更改的自包含集合，那么可以使用ICollection<T>或IList<T>。|1399877|例如，如果您希望返回搜索特定文件集的结果，则返回IEnumerable<FileInfo>。|1399878|但是，如果您希望公开目录中的文件，则需要公开IList/ICollection<FileInfo>，因为您可能希望更改集合的内容。|1399879|entityMap^0|Y|E|0|Q|E|15|8|0|O|L|0|M|R|0^^$0|@$1|2|3|4|5|6|7|N|8|@$9|O|A|P|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Q|8|@$9|R|A|S|B|C]|$9|T|A|U|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|V|8|@$9|W|A|X|B|C]]|D|@]|E|$]]|$1|J|3|K|5|6|7|Y|8|@$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|L|3|-4|5|6|7|11|8|@]|D|@]|E|$]]]|M|$]]

If the collection that is being returned is read-only, meaning you never want the elements to in the collection to be changed, then use <code>IEnumerable&lt;T&gt;</code>. This is the most basic representation of a read-only sequence of immutable (at least from the perspective of the enumeration itself) elements.

If you want it to be a self-contained collection that can be changed, then use <code>ICollection&lt;T&gt;</code> or <code>IList&lt;T&gt;</code>.

For example, if you wanted to return the results of searching for a particular set of files, then return <code>IEnumerable&lt;FileInfo&gt;</code>.

However, if you wanted to expose the files in a directory, however, you would expose <code>IList/ICollection&lt;FileInfo&gt;</code> as it makes sense that you would want to possibly change the contents of the collection.

blocks|key|1399768|text|return+ICollection<type>|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1399769|泛型返回类型的优点是，您可以更改基础实现，而无需更改使用它的代码。返回特定类型的好处是您可以使用更多特定于类型的方法。|unstyled|1399770|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|J|8|@]|9|@]|A|$]]|$1|G|3|-4|5|F|7|K|8|@]|9|@]|A|$]]]|H|$]]

<pre><code>return ICollection&lt;type&gt;
</code></pre>

The advantage to generic return types, is that you can change the underlying implementation without changing the code that uses it. The advantage to returning the specific type, is you can use more type specific methods.

blocks|key|1614282|text|始终返回向调用方呈现最多功能的接口类型。因此，在您的情况下，应该使用ICollection<YourType>。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1614283|有趣的是，BCL开发人员实际上在.NET框架的某些地方弄错了--请参阅this+Eric+Lippert+blog+post。|1614284|entityMap|0|LINK|mutability|MUTABLE|url|http://blogs.msdn.com/ericlippert/archive/2008/09/22/arrays-considered-somewhat-harmful.aspx^0|Y|L|0|Z|R|0|0^^$0|@$1|2|3|4|5|6|7|P|8|@$9|Q|A|R|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|S|8|@]|D|@$9|T|A|U|1|V]]|E|$]]|$1|H|3|-4|5|6|7|W|8|@]|D|@]|E|$]]]|I|$J|$5|K|L|M|E|$N|O]]]]

Always return an interface type that presents the greatest amount of functionality to the caller. So in your case <code>ICollection&lt;YourType&gt;</code> ought to be used.

Something interesting to note is that the BCL developers actually got this wrong in some place of the .NET framework - see <a href="http://blogs.msdn.com/ericlippert/archive/2008/09/22/arrays-considered-somewhat-harmful.aspx" rel="nofollow noreferrer">this Eric Lippert blog post</a> for that story.

blocks|key|1399788|text|为什么不使用IList<MyType>？|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1399789|它支持直接索引，这是数组的标志，而不会消除某一天返回List<MyType>的可能性。如果要取消此功能，可能需要返回IEnumerable<MyType>。|1399790|entityMap^0|6|D|0|Q|C|1M|J|0^^$0|@$1|2|3|4|5|6|7|J|8|@$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|H|3|-4|5|6|7|R|8|@]|D|@]|E|$]]]|I|$]]

Why not <code>IList&lt;MyType&gt;</code>?

It supports direct indexing which is hallmark for an array without removing the possibility to return a <code>List&lt;MyType&gt;</code> some day. If you want to suppress this feature, you probably want to return <code>IEnumerable&lt;MyType&gt;</code>.

blocks|key|1614875|text|这取决于您打算如何处理要返回的集合。如果您只是在迭代，或者如果您只想让用户迭代，那么我同意@Daniel，返回IEnumerable<T>。但是，如果您实际上想要允许基于列表的操作，我会返回IList<T>。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1614876|entityMap^0|1J|E|2N|8|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|M|8|@]|D|@]|E|$]]]|G|$]]

It depends on what you plan to do with the collection you're returning. If you're just iterating, or if you only want the user to iterate, then I agree with @Daniel, return <code>IEnumerable&lt;T&gt;</code>. If you actually want to allow list-based operations, however, I'd return <code>IList&lt;T&gt;</code>.

blocks|key|1614218|text|使用泛型。它更容易与其他集合类进行互操作，并且类型系统更能帮助您处理潜在的错误。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1614219|返回数组的旧风格是泛型之前的拐杖。|1614220|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

Use generics. It's easier to interoperate with other collections classes and the type system is more able to help you with potential errors.

The old style of returning an array was a crutch before generics.

blocks|key|1614376|text|让你的代码更具可读性、可维护性和易用性。大多数情况下，我会使用简单的数组simpler==better。虽然我真的要看上下文才能给出正确的答案。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1614377|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

What ever makes your code more readable, maintainable and easier for YOU.
I would have used the simple array, simpler==better most of the time. 
Although I really have to see the context to give the right answer.

blocks|key|1400005|text|与其他任何东西相比，支持IEnumerable有很大的优势，因为这为您提供了最大的实现灵活性，并允许您使用yield+return或Linq运算符进行延迟实现。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1400006|如果调用者想要一个List<T>，他们可以简单地对您返回的任何内容调用ToList()，总体性能将与您从方法中创建并返回一个新的List<T>大致相同。|1400007|entityMap^0|1H|C|0|9|7|Z|8|1S|7|0^^$0|@$1|2|3|4|5|6|7|J|8|@$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]|$9|R|A|S|B|C]]|D|@]|E|$]]|$1|H|3|-4|5|6|7|T|8|@]|D|@]|E|$]]]|I|$]]

There are big advantages to favouring IEnumerable over anything else, as this gives you the greatest implementation flexibility and allows you to use <code>yield return</code> or Linq operators for lazy implementation.

If the caller wants a <code>List&lt;T&gt;</code> instead they can simply call <code>ToList()</code> on whatever you returned, and the overall performance will be roughly the same as if you had created and returned a new <code>List&lt;T&gt;</code> from your method.

blocks|key|1614796|text|数组是有害的，但ICollection<T>也是有害的。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1614797|ICollection<T>不能保证对象是不可变的。|1614798|我的建议是用ReadOnlyCollection<T>包装返回的对象|1614799|entityMap^0|8|E|0|0|E|0|6|L|0^^$0|@$1|2|3|4|5|6|7|L|8|@$9|M|A|N|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|O|8|@$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|R|8|@$9|S|A|T|B|C]]|D|@]|E|$]]|$1|J|3|-4|5|6|7|U|8|@]|D|@]|E|$]]]|K|$]]

Array is harmful, but <code>ICollection&lt;T&gt;</code> is also harmful.

<code>ICollection&lt;T&gt;</code> cannot guarantee the object will be immutable.

My recommendation is to wrap the returning object with <code>ReadOnlyCollection&lt;T&gt;</code>

What's the preferred container type when returning multiple objects of the same type from a function? 

Is it against good practice to return a simple array (like MyType[]), or should you wrap it in some generic container (like ICollection&lt;MyType&gt;)? 

Thanks!

Should I return an array or a collection from a function?

容器

当从一个函数返回多个相同类型的对象时，首选的容器类型是什么？返回一个简单的数组(如MyType[])是违反良好实践的，还是应该将其包装在某个通用容器(如ICollection)中？谢谢!

问我应该从函数中返回一个数组还是一个集合？
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