实现接口 [英] Implementing an inteface

问题描述

我对接口的实现感到困惑。



ICollection< T> 有属性 IsReadOnly 根据 MSDN [ ^ ]

-And-

集合< T> impliments ICollection< T> 根据 MSDN [ ^ ]

-So-

我以为 Collection< T> 会有property IsReadOnly 。

-However-

I'm confused about the implementation of interfaces.

ICollection<T> has the property IsReadOnly according to MSDN[^]
-And-
Collection<T> impliments ICollection<T> according to MSDN[^]
-So-
I thought that Collection<T> would have the property IsReadOnly.
-However-

Collection<string> testCollection = new Collection<string>();
Console.WriteLine(testCollection.IsReadOnly);

上面的代码给出了编译错误：

'System.Collections.ObjectModel .Collection< string>'不包含'IsReadOnly'的定义，并且没有扩展方法'IsReadOnly'接受类型为'System.Collections.ObjectModel.Collection< string>'的第一个参数'（你是否缺少using指令）或汇编参考？）

-While-

The above code gives the compiler error:
'System.Collections.ObjectModel.Collection<string>' does not contain a definition for 'IsReadOnly' and no extension method 'IsReadOnly' accepting a first argument of type 'System.Collections.ObjectModel.Collection<string>' could be found (are you missing a using directive or an assembly reference?)
-While-

Collection<string> testInterface = new Collection<string>();
Console.WriteLine(((ICollection<string>)testInterface).IsReadOnly);

以上代码有效。

-Question-

我认为实现接口的类必须实现每个属性，所以为什么 testCollection 没有 IsReadOnly 属性，除非你将其转换为 ICollection< string> ？

The above code works.
-Question-
I thought classes implementing interfaces had to implement every property, so why doesn't testCollection have the IsReadOnly property unless you cast it as ICollection<string>?

推荐答案

IsReadOnly [ ^ ]属性明确实现。这意味着只有在将对象显式转换为ICollection< t>时才能调用此属性。



可以找到有关显式接口实现的更多信息其中 [ ^ ]

The IsReadOnly[^] property is implemented explicitely. That means you can only call this property when the object is explicitly cast to an ICollection<t>.

More info about explicit interface implementation can be found here[^]

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