Platform::Collections::Map - with enum as key

Question

Im a c# dev trying to get into c++, and Im writing some custom controls. I need the c++ equivalent of the following complex c# Dictionary

private static Dictionary<PinchscapeColor, 
        Dictionary<PinchscapeColorLevel, Brush>> AccentColorMap;

PinchscapeColor and PinchscapeColorLevel are simple c# enums

public enum PinchscapeColorLevel
{
    Light,
    Medium
    Dark
}

public enum PinchscapeColor
{
    PinchscapeCyan,
    PinchscapeLime,
    PinchscapeMagenta,
    PinchscapeTangerine,
    PinchscapePlum
}

and I calculate a particular color/color level combination like this (in c#)

var color = AccentColorMap[PinchscapeColor.PinchscapeCyan][PinchscapeColorLevel.Dark];

my attempts to do this in c++ have succeeded up to a point:

my enums:

public enum class PinchscapeColorLevel
{
    Light,
    Medium,
    Dark
};

public enum class PinchscapeColor
{
    PinchscapeCyan,
    PinchscapeLime,
    PinchscapeMagenta,
    PinchscapeTangerine,
    PinchscapePlum
};

ive defined a map in my header file like this

Platform::Collections::Map<PinchscapeBasicControls::PinchscapeColor,
    Platform::Collections::Map<PinchscapeBasicControls::PinchscapeColorLevel,
    Windows::UI::Xaml::Media::Brush^>^>^ colorMap;

but Im getting the following compiler error:

program files (x86)\microsoft visual studio 11.0\vc\include\collection.h(1118): error C3986: 'Invoke': signature of public member contains native type 'std::less<_Ty>' (that's the first line, it goes on forever)

Does anyone have any ideas what Im doing wrong ? Id have imagined that this was gonna be easy :(

EDIT

Please find below a minimal code example that is all the code you need to replicate the issue:

1) Class1.h

#pragma once

namespace WindowsRuntimeComponent1
{
    public enum class ColorLevelEnum
    {
        Light,
        Medium,
        Dark
    };

    public enum class ColorEnum
    {
        Cyan,
        Lime,
        Magenta,
        Tangerine,
        Plum
    };

    public ref class Class1 sealed
    {
    private:
        Windows::Foundation::Collections::IMap<WindowsRuntimeComponent1::
            ColorEnum,Windows::Foundation::Collections::IMap<WindowsRuntimeComponent1::
            ColorLevelEnum,Windows::UI::Xaml::Media::Brush^>^>^ colorMap;
    public:
        Class1();
    };
}

Class1.cpp

#include "pch.h"
#include <collection.h>
#include "Class1.h"

using namespace WindowsRuntimeComponent1;
using namespace Windows::UI::Xaml::Media;
using namespace Platform::Collections;
using namespace Platform;

Class1::Class1()
{
    if (colorMap == nullptr)
    {
        colorMap = ref new Map<ColorEnum,Map<ColorLevelEnum,Brush^>^>();
    }
}

hope that helps you recreate the issue

Thanks to anyone who is taking the time to help me sort this out

Answer 1

Your code as it is presented in the question is well-formed and compiles without error using the RTM release of Visual Studio 2012.

I can speculate, though, as to the cause of your problem: it is likely that you are using this colorMap (or its type) as a public or protected member of a public ref class or that you are using it in some way that its type ends up being the type of a public or protected member.

The Platform::Collections::Map type is a C++/CX-specific implementation of the interface Windows::Foundation::Collections::IMap. When declaring public members of a Windows Runtime type, you need to use IMap, not Map, since Map relies on C++- and C++/CX-specific language features that are not usable across the Windows Runtime ABI.

In short, if you change your colorMap to use IMap, it should solve the problem:

IMap<
    PinchscapeColor,
    IMap<
        PinchscapeColorLevel,
        Brush^
    >^
>^ colorMap;

When you instantiate this, you'll need to instantiate the outer map first, then each of the inner maps, using he Platform::Collections::Map. For example:

// Create the outer map; note the "value type" is still IMap<T, U>
colorMap = ref new Map<ColorEnum,IMap<ColorLevelEnum,Brush^>^>();

// Insert an element into the outer map:
colorMap->Insert(ColorEnum::Cyan, ref new Map<ColorLevelEnum, Brush^>());

---

Consider using some typedefs to make the code clearer:

typedef IMap<PinchscapeColorLevel, Brush^>          IColorLevelBrushMap;
typedef IMap<PinchscapeColor, IColorLevelBrushMap^> IColorMap;

IColorMap^ colorMap;

---

Alternatively, if you don't need to make this map accessible to other Windows Runtime components, consider using std::map, which will perform measurably better:

typedef std::map<PinchscapeColorLevel, Brush^>        ColorLevelBrushMap;
typedef std::map<PinchscapeColor, ColorLevelBrushMap> ColorMap;

ColorMap colorMap;

Or:

typedef std::pair<PinchscapeColor, PinchscapeColorLevel> ColorMapKey;
typedef std::map<ColorMapKey, Brush^>                    ColorMap;

ColorMap colorMap;