Question

I’m likely doing something boneheaded here, and I’d like a pointer (pardon the pun).

I’ve defined the following class:

ref class CoordinatePair {
public:
    int x;
    int y;
    CoordinatePair();
    CoordinatePair(int xInput, int yInput);
    CoordinatePair(CoordinatePair ^Other);
    //CoordinatePair& operator->();
};

Fairly simple. I find that I can select members using the -> operator within the class’s namespace with no ill effects. For example, the following compiles:

CoordinatePair::CoordinatePair(CoordinatePair ^Other) {
    x = Other->x;
    y = Other->y;
}

Groovy. Yet, when I try to compile this, I get problems.

CoordinatePair^ Coordinates::TranslateCoords(CoordinatePair^ WorldCoords) {
    CoordinatePair^ newCoords = gcnew CoordinatePair();
    float coordsRatio = 0.0;
    //Translate X
    coordsRatio = (float) WorldCoords->x / WorldBounds->x;
    newCoords->x = (int) (coordsRatio * PixelBounds->x);
    //Translate Y
    coordsRatio = 0.0;
    coordsRatio = (float) WorldCoords->y / WorldBounds->y;
    newCoords->y = (int) (coordsRatio * PixelBounds->y);
    return newCoords;
}

(Note, in the above code, WorldBounds is a member of the Coordinates class. It itself is a CoordinatePair that defines the plane for my project.)

Specifically I get this error:

.\Coordinates.cpp(95) : error C2819: type 'CoordinatePair' does not have an overloaded member 'operator ->'

Huh. Well, okay. My attempt to research this problem drove me to try overloading the operator. So, I added the following in the class declaration:

CoordinatePair^ operator->();

And I defined it like so:

CoordinatePair^ CoordinatePair::operator->() {
    return this;
}

That made the compiler even angrier! 🙁

.\Coordinates.cpp(17) : error C2818: application of overloaded 'operator ->' is recursive through type 'CoordinatePair'
        y:\documents\wende-project\c3\wende_c3_executioncode\wende_c3_executioncode\c3_display\c3_app\Coordinates.h(7) : see declaration of 'CoordinatePair'
.\Coordinates.cpp(17) : warning C4280: 'operator ->' was self recursive through type 'CoordinatePair'
        y:\documents\wende-project\c3\wende_c3_executioncode\wende_c3_executioncode\c3_display\c3_app\Coordinates.h(7) : see declaration of 'CoordinatePair'
.\Coordinates.cpp(18) : error C2818: application of overloaded 'operator ->' is recursive through type 'CoordinatePair'
        y:\documents\wende-project\c3\wende_c3_executioncode\wende_c3_executioncode\c3_display\c3_app\Coordinates.h(7) : see declaration of 'CoordinatePair'
.\Coordinates.cpp(18) : warning C4280: 'operator ->' was self recursive through type 'CoordinatePair'
        y:\documents\wende-project\c3\wende_c3_executioncode\wende_c3_executioncode\c3_display\c3_app\Coordinates.h(7) : see declaration of 'CoordinatePair'
.\Coordinates.cpp(62) : error C2818: application of overloaded 'operator ->' is recursive through type 'CoordinatePair'
        y:\documents\wende-project\c3\wende_c3_executioncode\wende_c3_executioncode\c3_display\c3_app\Coordinates.h(7) : see declaration of 'CoordinatePair'
.\Coordinates.cpp(62) : warning C4280: 'operator ->' was self recursive through type 'CoordinatePair'
        y:\documents\wende-project\c3\wende_c3_executioncode\wende_c3_executioncode\c3_display\c3_app\Coordinates.h(7) : see declaration of 'CoordinatePair'
.\Coordinates.cpp(62) : error C2818: application of overloaded 'operator ->' is recursive through type 'CoordinatePair'
        y:\documents\wende-project\c3\wende_c3_executioncode\wende_c3_executioncode\c3_display\c3_app\Coordinates.h(7) : see declaration of 'CoordinatePair'
.\Coordinates.cpp(62) : warning C4280: 'operator ->' was self recursive through type 'CoordinatePair'
        y:\documents\wende-project\c3\wende_c3_executioncode\wende_c3_executioncode\c3_display\c3_app\Coordinates.h(7) : see declaration of 'CoordinatePair'
.\Coordinates.cpp(62) : error C2818: application of overloaded 'operator ->' is recursive through type 'CoordinatePair'
        y:\documents\wende-project\c3\wende_c3_executioncode\wende_c3_executioncode\c3_display\c3_app\Coordinates.h(7) : see declaration of 'CoordinatePair'
.\Coordinates.cpp(62) : warning C4280: 'operator ->' was self recursive through type 'CoordinatePair'
        y:\documents\wende-project\c3\wende_c3_executioncode\wende_c3_executioncode\c3_display\c3_app\Coordinates.h(7) : see declaration of 'CoordinatePair'
.\Coordinates.cpp(62) : error C2818: application of overloaded 'operator ->' is recursive through type 'CoordinatePair'
        y:\documents\wende-project\c3\wende_c3_executioncode\wende_c3_executioncode\c3_display\c3_app\Coordinates.h(7) : see declaration of 'CoordinatePair'
.\Coordinates.cpp(62) : warning C4280: 'operator ->' was self recursive through type 'CoordinatePair'
        y:\documents\wende-project\c3\wende_c3_executioncode\wende_c3_executioncode\c3_display\c3_app\Coordinates.h(7) : see declaration of 'CoordinatePair'
.\Coordinates.cpp(95) : error C2818: application of overloaded 'operator ->' is recursive through type 'CoordinatePair'
        y:\documents\wende-project\c3\wende_c3_executioncode\wende_c3_executioncode\c3_display\c3_app\Coordinates.h(7) : see declaration of 'CoordinatePair'
.\Coordinates.cpp(95) : warning C4280: 'operator ->' was self recursive through type 'CoordinatePair'
        y:\documents\wende-project\c3\wende_c3_executioncode\wende_c3_executioncode\c3_display\c3_app\Coordinates.h(7) : see declaration of 'CoordinatePair'
.\Coordinates.cpp(95) : error C2818: application of overloaded 'operator ->' is recursive through type 'CoordinatePair'
        y:\documents\wende-project\c3\wende_c3_executioncode\wende_c3_executioncode\c3_display\c3_app\Coordinates.h(7) : see declaration of 'CoordinatePair'
.\Coordinates.cpp(95) : warning C4280: 'operator ->' was self recursive through type 'CoordinatePair'
        y:\documents\wende-project\c3\wende_c3_executioncode\wende_c3_executioncode\c3_display\c3_app\Coordinates.h(7) : see declaration of 'CoordinatePair'

Looking up the error gave me the following definition:

application of overloaded ‘operator ->’ is recursive through type ‘type’

A redefinition of the class member access operator contains a recursive return statement. To redefine the -> operator with recursion, you must move the recursive routine to a separate function called from the operator override function.

I clearly don’t know what I’m doing here and need to be set in the right direction. Help?

Answer 1

As Patrick said in the comments, you’ve got WorldBounds as type CoordinatePair when it should be CoordinatePair^. As you mentioned, that fix causes other compiler errors, you’ll need to go through all the places you currently do WorldBounds.x and replace it with WorldBounds->x.

For a ref class, you’ll almost always want to use the ^. There are situations where you’ll want to leave it off, but they’re rare.