c# - 无法将 C# 代码移植到实现 IDataErrorInfo 的托管 C++

Question

这部分。注释代码是cs。在编译时捕获错误:

Error   78
error C3766: 'Sample::NoteInfo' must provide an implementation for the interface method 'System::String ^System::ComponentModel::IDataErrorInfo::default::get(System::String ^)'
d:\dev\docstreet\sample\pointInfoStoreClass.h   100

哪里不对？为什么 VS 编译器认为这没有实现？

//Returns an error description set for the item's property
//String^ IDataErrorInfo.this[String^ columnName] {
//  get {
//      return GetColumnError(columnName);
//  }
//}

public: property String^ IDataErrorInfo[String^] {
    virtual String^ get(String^ index) override {
        return GetColumnError(index);
    }
}

完整代码:

public ref class NoteInfo : IDataErrorInfo {
        int fDay;
        int fMonth;
        int fYear;
        int fNoteID;
        //References the item's owner
        ProjectNotes^ owner;
        //Stores error descriptions for the Day, Month, Year and NoteID properties
        Hashtable^ propertyErrors;
        //Stores an error description for the item
        String^ fNoteError;


    public: NoteInfo(int noteID, int day, int month, int year) {
            fNoteID = noteID;
            fDay = day;
            fMonth = month;
            fYear = year;
            //Set errors to empty strings
            propertyErrors = gcnew Hashtable();
            propertyErrors->Add('Day', '');
            propertyErrors->Add('Month', '');
            propertyErrors->Add('Year', '');
            propertyErrors->Add('NoteID', '');
            fNoteError = '';
            Owner = nullptr;
        }

    public: property int NoteID {
            int get() { return fNoteID; }
            void set(int value) {
                if(fNoteID == value) return;
                fNoteID = value;
            }
        }

    public: void ClearErrors() {
            SetColumnError('Day', '');
            SetColumnError('Month', '');
            SetColumnError('Year', '');
            fNoteError = '';
        }

        //Sets an error for an item's property
    public: void SetColumnError(String^ elem, String^ error) {
            if(propertyErrors->ContainsKey(elem)) {
                if((String^)propertyErrors[elem] == error) return;
                propertyErrors[elem] = error;
            }
        }

        //Gets an error for an item's property
    public: String^ GetColumnError(String^ elem) {
            if(propertyErrors->ContainsKey(elem))
                return (String^)propertyErrors[elem];
            else
                return '';
        }

        //The owner collection
    internal: property ProjectNotes^ Owner {
            ProjectNotes^ get() { return owner; }
            void set(ProjectNotes^ value) { owner = value; }
        }


#pragma region IDataErrorInfo Members

        //Returns an error description set for the item's property
        //String^ IDataErrorInfo.this[String^ columnName] {
        //  get {
        //      return GetColumnError(columnName);
        //  }
        //}

        public: property String^ IDataErrorInfo[String^] {
            virtual String^ get(String^ index) override {
                return GetColumnError(index);
            }
        }

        //Returns an error description set for the current item
    public: property String^ Error {
            virtual String^ get() { return fNoteError; }

        }
#pragma endregion
    };

Answer 1

C# 和 C++/CLI 语言都需要一个类的索引器的特殊名称，以允许编译器将其识别为索引器。 C# 使用 this，C++/CLI 使用 default 关键字。 MSDN 库将其称为“Item”以增加混淆，这在某种程度上是不可避免的，因为名称取决于语言。所以它必须看起来像这样:

public: property String^ default[String^] {
            virtual String^ get(String^ index) {
                // etc...
            }
        }