[C++] Any

#ifndef __OSHGUI_MISC_ANY_H__
#define __OSHGUI_MISC_ANY_H__
 
namespace OSHGui
{
	namespace Misc
	{
		/**
		 * Dieser Datentyp kann jeden anderen Datentyp aufnehmen.
		 */
		class Any
		{
		private:
			//Verhindert "ISO C++ forbids declaration of 'TypeWrapper' with no type"
			class AnyTypeWrapper
			{
			public:
				virtual ~AnyTypeWrapper() { }
				virtual AnyTypeWrapper* Copy() = 0;
				virtual void* GetObject() = 0;
			};
			//---------------------------------------------------------------------------
			template<class T> class TypeWrapper : public AnyTypeWrapper
			{
			private:
				T obj;
 
			public:
				TypeWrapper(const T &object) : obj(object) { }
				//---------------------------------------------------------------------------
				TypeWrapper* Copy()
				{
					return new TypeWrapper<T>(obj);
				}
				//---------------------------------------------------------------------------
				void* GetObject()
				{
					return &obj;
				}
			};
			//---------------------------------------------------------------------------
			unsigned int id;
			AnyTypeWrapper *wrapper;
			//---------------------------------------------------------------------------
			static unsigned int NextID()
			{
				static unsigned int id = 0;
				++id;	
				return id;
			}
			//---------------------------------------------------------------------------
			template<class T> static unsigned int TypeID()
			{
				static unsigned int id = NextID();
				return id;
			}
			//---------------------------------------------------------------------------
 
		public:
			/**
			 * Erzeugt ein leeres Any-Objekt.
			 */
			Any()
			{
				id = 0;
				wrapper = 0;
			}
			/**
			 * Erzeugt ein Any-Objekt, das das angegebene Objekt enthält.
			 *
			 * @param obj
			 */
			template<class T> Any(const T &obj)
			{
				id = TypeID<T>();
				wrapper = new TypeWrapper<T>(obj);
			}
			/**
			 * Kopierkonstruktor
			 */
			Any(const Any &any)
			{
				delete wrapper;
 
				id = any.id;
				wrapper = any.wrapper->Copy();
			}
			/**
			 * Weißt diesem Any-Objekt das angegebene zu.
			 *
			 * @param any
			 * @return this
			 */
			Any& operator= (Any const& any)
			{
				if (this != &any)
				{
					delete wrapper;
 
					id = any.id;
					wrapper = any.wrapper->Copy();
				}
				return *this;
			}
			/**
			 * Dieser Operator erlaubt per if (!any) { any ist leer } zu prüfen, ob das Any-Objekt leer ist.
			 */
			operator void *() const
			{
				return (wrapper == 0 ? 0 : (void*)this);
			}
 
			~Any()
			{
				delete wrapper;
			}
 
			/**
			 * Castet ein Any-Objekt zu dem in ihm befindlichen Datentyp. Falls ein falscher Datentyp angegeben wird,
			 * wird eine Exception ausgelöst.
			 *
			 * @return das aufgenommene Objekt
			 */
			template<class T> T CastTo()
			{
				if (TypeID<T>() == id)
				{
					return *static_cast<T*>(wrapper->GetObject());
				}
				else
				{
					throw 1;
				}
			}
		};
	}
}
 
#endif

#include <iostream>
#include <string>
#include "Any.h"
 
int main()
{
	Any anything[5];
	anything[0] = (int)1337;
	anything[1] = (char*)"char*";
	anything[2] = (float)1.337f;
	anything[3] = std::string("std::string");
	anything[4] = true;
 
	std::cout << anything[0].CastTo<int>() << std::endl
			  << anything[1].CastTo<char*>() << std::endl
			  << anything[2].CastTo<float>() << std::endl
			  << anything[3].CastTo<std::string>() << std::endl
			  << anything[4].CastTo<bool>() << std::endl;
 
	return 0;
}

try
{
	float f = anything[0].CastTo<float>();
}
catch (...)
{
	std::cout << "ist kein float!" << std::endl;
}