我们可以在不使用 IEnumerable 接口的情况下使用 GetEnumerator() 吗？
我有一个名为 Primes 的类，该类实现 GetEnumerator() 而不实现 IEnumerable 接口。
public class Primes
{
private long min;
private long max;
public Primes()
: this(2, 100)
{
}
public IEnumerator GetEnumerator()
{...}
我不明白。我错过了什么吗？
I have a class called Primes and this class implements GetEnumerator() without implementing IEnumerable interface.
public class Primes
{
private long min;
private long max;
public Primes()
: this(2, 100)
{
}
public IEnumerator GetEnumerator()
{...}
I don't get it. Am I missing something?
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首先，正如其他人所说，您可以在不实现接口的情况下引入自己的方法 - 您可以编写自己的
Dispose方法而不实现IDisposable等。对于众所周知的接口，我'我认为这几乎是一个坏主意（因为读者会有一定的期望），但它是完全有效的。但更重要的是，C# 中的
foreach语句可以在不涉及IEnumerable的情况下工作。编译器有效地对名称GetEnumerator()、Current和MoveNext()执行编译时鸭子类型。这主要是为了在泛型之前允许 C# 1 中的强类型（和非装箱）迭代。有关更多详细信息，请参阅 C# 3 规范的第 8.8.4 节。然而，如果您希望能够轻松地将实例的内容作为集合进行迭代，那么现在这样做通常是一个坏主意 - 事实上，我建议实现
IEnumerable< T>而不仅仅是IEnumerable。Firstly, as others have said you can introduce your own methods without implementing interfaces anyway - you can write your own
Disposemethod without implementingIDisposableetc. For well-known interfaces I'd suggest this is almost a bad idea (as readers will have certain expectations) but it's entirely valid.More importantly though, the
foreachstatement in C# can work withoutIEnumerablebeing involved. The compiler effectively does compile-time duck typing on the namesGetEnumerator(),CurrentandMoveNext(). This was primarily to allow strongly-typed (and non-boxing) iteration in C# 1, before generics. See section 8.8.4 of the C# 3 spec for more details.However, it's generally a bad idea to do this now if you do want to be able to easily iterate over the contents of an instance as a collection - and indeed I'd suggest implementing
IEnumerable<T>instead of justIEnumerable.是的，你可以。甚至你可以在
foreach中使用它。唯一的问题是此类的对象无法转换为 IEnumerable，尽管它们实现了所需的方法。yes you can. even you can use it in
foreach. The only problem that objects of this class can't be cast toIEnumerablealthough they implement needed method.您没有理由必须实现
IEnumerable才能创建一个名为GetEnumerator并返回IEnumerator的函数，这只意味着您不会'无法为需要 IEnumerable 的对象提供该类型的实例。There's no reason that you have to implement
IEnumerablein order to create a function calledGetEnumeratorthat returns anIEnumerator, that just means that you won't be able to supply an instance of that type to something that expects anIEnumerable.接口确保契约，这并不意味着您不能在未实现该接口的类上拥有与接口中的签名相同的方法。
an interface ensures a contract, that does not mean that you can't have a method with the same signature as one in the interface on a class that does not impliment the interface.