[VSDK ] Access to cursor fields

[Eric Forget]

> By the way, anybody have idea how to access VALUES of fields of cursor
> In more short way ?
> 
> I consider in 2.0 provide as alternative cursor with binding to true C++
> variables (old know way). Underline as alternative. So each can choose what
> is better for him.
> 
> But may be something else ?

Yep it is possible. I don't remember the name of this method which I read 2
years ago in Modern C++ Design (from Andrei Alexandrescu).

What we want is this:

short   myShort     = curs->GetValue("Field1");
char    *myCharPtr  = curs->GetValue("Field2");
long    myLong      = curs->GetValue("Field3");

For this to work there is a simple trick. You cannot have overloading of
functions which differ only by return code. However, you can return a
temporary object instead:

class VDK_TempReturnValue
{
public:
                    VDK_TempReturnValue(
                        VDK_Cursor &inCursor,
                        const char* inFieldName)
                        : mCurs(inCursor), mName(inName) {}

                    operator short() const
                    {
                        VDK_Short* field = mc->GetShortField(mName);

                        return (short)*field;
                    }

                    operator long() const
                    {
                        VDK_Long* field = mc->GetLongField(mName);

                        return (long)*field;
                    }

                    operator char *() const
                    {
                        VDK_Text* field = mc->GetTextField(mName);

                        return (char *)*field;
                    }


protected:
    VDK_Cursor      &mCurs;
    const char *    mName;
};

And then for your VDK_Cursor:

class VDK_Cursor
{
public:
    VDK_TempReturnValue  GetValue(const char* inName) const
                         {
                            return VDK_TempReturnValue(*this, inName);
                         }
};

You will have to support GetValue(ushort index) too, but I think you get the
idea...

Éric

___________________________________________________________________

 Eric Forget                       Cafederic
 ForgetE at cafederic.com             <http://www.cafederic.com/>

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