Implementing an interface declared in C# from C++/CLI

Question

Say I have a C# interface called IMyInterface defined as follows:

// C# code public interface IMyInterface {   void Foo(string value);   string MyProperty { get; } } 

Assume I also have a C++/CLI class, MyConcreteClass, that implements this interface and whose header is declared as follows:

// C++/CLI header file ref class MyConcreteClass : IMyInterface { public:  }; 

How does one implement the method Foo and the property MyProperty in the C++/CLI header?

My attempt results in the following compile error:

error C3766: 'MyConcreteClass' must provide an implementation for the interface method 'void IMyInterface::Foo(System::String^ value)'

Answer 1

public ref class MyConcreteClass : public IMyInterface {  public:   virtual void __clrcall Foo(String^ value) sealed;      virtual property String^ __clrcall MyProperty           { String^ get() sealed { String::Empty; } } }; 

Interfaces need to be defined as virtual. Also note the "public IMy.." after the class decleration, it's a slighly different syntax than C#.

If you can, seal the interface members to improve performance, the compiler will be able to bind these methods more tightly than a typical virtual members.

Hope that helps ;)

I did not compile it but looks good to me... Oh and also, defining your methods as __clrcall eliminates dangers of double thunk performance penalties.

edit the correct syntax for a property is:

public ref class MyConcreteClass : public IMyInterface {  public:   virtual property String^ MyProperty    {     String^ get() sealed { return String::Empty; };     void set( String^ s ) sealed { };   } }; 

or, when putting the definition in the source file:

public ref class MyConcreteClass : public IMyInterface {  public:   virtual property String^ MyProperty    {     String^ get() sealed;     void set( String^ s ) sealed;   } };  String^ MyConcreteClass::MyProperty::get() {   return String::Empty; }  void MyConcreteClass::MyProperty::set( String^ ) {   //... }