(newbie) How to initialize a private static member..

Question

I'm trying to play with WinRT/C++ (I'm new to C++ but WinRT / XAML C++ UI are convincing me to give C++ another go!)

 

At any rate, I'm trying to write some helper code to implement ICustomPropertyProvider.

I have a class implementing ICustomPropertyProvider that can be build programatically and I'm trying to have a static instance member of it to have one members map per class.

 

Something like that:

#pragma once
#include "pch.h"

using namespace Windows::Foundation;
using namespace Experiments::MetaInfo;

namespace Experiments
{
    public delegate void SomeEventHandler(int i);

	public ref class Model sealed : public ViewModelBase, public ICustomPropertyProvider, public IDisposable
    {
	private:
		ref class ModelPropertyProvider : PropertyProvider
		{
			ModelPropertyProvider()
			{
				//AddCustomProperty(
				//	ref new PropertyInfo(
				//		"PropertyA"
				//		, "int"
				//		, ref new PropertyGetter([](Object^ instance) {return PropertyValue::CreateInt32(((WinRTComponent^)instance)->PropertyA);})
				//		, ref new PropertySetter([](Object^ instance, Object^ value) {((WinRTComponent^)instance)->PropertyA = ((PropertyValue^)value)->GetInt32();})
				//	)
				//);
			}
		};
		<strong>static ModelPropertyProvider myPProvider</strong>;
		// this macro implement ICustomPropertyProvider
		PROPERTY_PROVIDER_IMPL("Model", myPProvider);
	public:

	private:
        int mPropertyA;

	protected:

    public:
        Model ()
		{
			mPropertyA = 23;
		}
		~Model () {}

        property int PropertyA
        {
            int get() 
			{
				return mPropertyA; 
			}
            void set(int propertyAValue) 
			{
				if (propertyAValue == mPropertyA)
					return;
				mPropertyA = propertyAValue; 
				FirePropertyChanged("PropertyA");
			}
        }

		property String^ PropertyS
        {
            String^ get() { return "Hello"; }
            void set(String^ p) 
			{
			}
        }

		//int Method(int i) { return i; }

        //event SomeEventHandler^ someEvent;

    };
}
// Model.h

But when I try to compile and use this class in my project I got error along the lines:

Error 1 error LNK2005: "private: static class Experiments::Model::ModelPropertyProvider Experiments::Model::myPProvider" (?myPProvider@Model@Experiments@@0VModelPropertyProvider@12@A) already defined in MainPage.xaml.obj C:\Dev\Tests\Mix2\Experiments\Model.obj Experiments

I have been poking at the code for 1 hour now, I didn't find a way to initialize my private static member variable (of a type of a private class). (make it a pointer or not)

Any tip on how I can this thing to compile??

Thanks! :)