一个神奇的???whatever~~

一个神奇的类，用来封装消息数据，统一数据传递接口，从unity引擎源码拷贝而来。

#include <iostream>
#include <assert.h>
#include <crtdefs.h>

struct MessageData
{
	int type;
private:
	// Note: on Metro WinRT types cannot be located in union, so don't use union!
	intptr_t data;

public:
	MessageData ()
	{
		data = 0; type = 0;
	}

	template<class T>
	void SetData (T inData, int classId)
	{
		// Check if SetData is used instead of SetScriptingObjectData
		//assert (type !=-1);
		//assert (sizeof (T) > sizeof (data)); // increase the data size
		*reinterpret_cast<T*> (&data) = *reinterpret_cast<T*> (&inData);
		type = classId;
	}

	template<class T>
	T GetData ()
	{
		// Check if GetData is used instead of GetScriptingObjectData
		assert (type != -1);
		return *reinterpret_cast<T*> (&data);
	}

	intptr_t& GetGenericDataRef ()
	{
		// Check if GetGenericDataRef is used instead of GetScriptingObjectData
		assert (type != -1);
		return data;
	}
};

class test
{
public:
	test(int x)
	{
		m_date = x;
	}

	void print()
	{
		std::cout<<m_date<<std::endl;
	}

private:
	int m_date ;
};

int main()
{
	MessageData data;
	test t(4);
	data.SetData(&t, 2);

	test * tt = data.GetData<test*>();
	tt->print();
	return 0;
}