泛型接口 (C++/CLI)

类和接口中的类型参数要遵循的限制相同(请参阅泛型类 (C++/CLI))。

对于泛型类或泛型接口中的函数,控制函数重载的规则是相同的。

显式接口成员实现处理构造接口类型和简单接口类型的方式相同(请参阅下面的示例)。

若要详细了解接口,请参阅 interface class

语法

[attributes] generic <class-key type-parameter-identifier[, ...]>
[type-parameter-constraints-clauses][accesibility-modifiers] interface class identifier [: base-list] {   interface-body} [declarators] ;

备注

attributes
(可选)其他声明性信息。 若要详细了解特性和特性类,请参阅“attribute”

class-key
classtypename

type-parameter-identifier(s)
标识符的逗号分隔列表。

type-parameter-constraints-clauses
采用泛型类型参数的约束 (C++/CLI) 中指定的形式

accessibility-modifiers
(可选)可访问性修饰符(例如,public、private)。

identifier
接口名称。

base-list
(可选)包含一个或多个显式基接口的逗号分隔列表。

interface-body
接口成员的声明。

declarators
(可选)基于此类型的变量的声明。

示例:如何声明和实例化泛型接口

下面的示例展示了如何声明和实例化泛型接口。 此示例声明泛型接口 IList<ItemType>。 然后,两个泛型类(List1<ItemType>List2<ItemType>)通过不同实现来实现它。

// generic_interface.cpp
// compile with: /clr
using namespace System;

// An exception to be thrown by the List when
// attempting to access elements beyond the
// end of the list.
ref class ElementNotFoundException : Exception {};

// A generic List interface
generic <typename ItemType>
public interface class IList {
   ItemType MoveFirst();
   bool Add(ItemType item);
   bool AtEnd();
   ItemType Current();
   void MoveNext();
};

// A linked list implementation of IList
generic <typename ItemType>
public ref class List1 : public IList<ItemType> {
   ref class Node {
      ItemType m_item;

   public:
      ItemType get_Item() { return m_item; };
      void set_Item(ItemType value) { m_item = value; };

      Node^ next;

      Node(ItemType item) {
         m_item = item;
         next = nullptr;
      }
   };

   Node^ first;
   Node^ last;
   Node^ current;

   public:
   List1() {
      first = nullptr;
      last = first;
      current = first;
   }

   virtual ItemType MoveFirst() {
      current = first;
      if (first != nullptr)
        return first->get_Item();
      else
         return ItemType();
   }

   virtual bool Add(ItemType item) {
      if (last != nullptr) {
         last->next = gcnew Node(item);
         last = last->next;
      }
      else {
         first = gcnew Node(item);
         last = first;
         current = first;
      }
      return true;
   }

   virtual bool AtEnd() {
      if (current == nullptr )
        return true;
      else
        return false;
   }

   virtual ItemType Current() {
       if (current != nullptr)
         return current->get_Item();
       else
         throw gcnew ElementNotFoundException();
   }

   virtual void MoveNext() {
      if (current != nullptr)
       current = current->next;
      else
        throw gcnew ElementNotFoundException();
   }
};

// An array implementation of IList
generic <typename ItemType>
ref class List2 : public IList<ItemType> {
   array<ItemType>^ item_array;
   int count;
   int current;

   public:

   List2() {
      // not yet possible to declare an
      // array of a generic type parameter
      item_array = gcnew array<ItemType>(256);
      count = current = 0;
   }

   virtual ItemType MoveFirst() {
      current = 0;
      return item_array[0];
   }

   virtual bool Add(ItemType item) {
      if (count < 256)
         item_array[count++] = item;
      else
        return false;
      return true;
   }

   virtual bool AtEnd() {
      if (current >= count)
        return true;
      else
        return false;
   }

   virtual ItemType Current() {
      if (current < count)
        return item_array[current];
      else
        throw gcnew ElementNotFoundException();
   }

   virtual void MoveNext() {
      if (current < count)
         ++current;
      else
         throw gcnew ElementNotFoundException();
   }
};

// Add elements to the list and display them.
generic <typename ItemType>
void AddStringsAndDisplay(IList<ItemType>^ list, ItemType item1, ItemType item2) {
   list->Add(item1);
   list->Add(item2);
   for (list->MoveFirst(); ! list->AtEnd(); list->MoveNext())
   Console::WriteLine(list->Current());
}

int main() {
   // Instantiate both types of list.

   List1<String^>^ list1 = gcnew List1<String^>();
   List2<String^>^ list2 = gcnew List2<String^>();

   // Use the linked list implementation of IList.
   AddStringsAndDisplay<String^>(list1, "Linked List", "List1");

   // Use the array implementation of the IList.
   AddStringsAndDisplay<String^>(list2, "Array List", "List2");
}
Linked List
List1
Array List
List2

示例:声明泛型接口

下面的示例声明一个泛型接口 IMyGenIface,以及两个专用化 IMyGenIface 的非泛型接口(IMySpecializedIntImySpecializedString)。 然后,两个专用化接口由两个类(MyIntClassMyStringClass)实现。 此示例展示了如何专用化泛型接口、如何实例化泛型接口和非泛型接口,以及如何调用接口中已显式实现的成员。

// generic_interface2.cpp
// compile with: /clr
// Specializing and implementing generic interfaces.
using namespace System;

generic <class ItemType>
public interface class IMyGenIface {
   void Initialize(ItemType f);
};

public interface class IMySpecializedInt: public IMyGenIface<int> {
   void Display();
};

public interface class IMySpecializedString: public IMyGenIface<String^> {
   void Display();
};

public ref class MyIntClass: public IMySpecializedInt {
   int myField;

public:
   virtual void Initialize(int f) {
      myField = f;
   }

   virtual void Display() {
      Console::WriteLine("The integer field contains: {0}", myField);
   }
};

public ref struct MyStringClass: IMySpecializedString {
   String^ myField;

public:
   virtual void Initialize(String^ f) {
      myField = f;
    }

   virtual void Display() {
      Console::WriteLine("The String field contains: {0}", myField);
   }
};

int main() {
   // Instantiate the generic interface.
   IMyGenIface<int>^ myIntObj = gcnew MyIntClass();

   // Instantiate the specialized interface "IMySpecializedInt."
   IMySpecializedInt^ mySpIntObj = (IMySpecializedInt^) myIntObj;

   // Instantiate the generic interface.
   IMyGenIface<String^>^ myStringObj = gcnew MyStringClass();

   // Instantiate the specialized interface "IMySpecializedString."
   IMySpecializedString^ mySpStringObj =
            (IMySpecializedString^) myStringObj;

   // Call the explicitly implemented interface members.
   myIntObj->Initialize(1234);
   mySpIntObj->Display();

   myStringObj->Initialize("My string");
   mySpStringObj->Display();
}
The integer field contains: 1234
The String field contains: My string

另请参阅

泛型