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用宏实现 C++ Singleton 模式

  Singleton 设计模式应用非常广泛,实现起来也很简单,无非是私有化若干个构造函数,“operator =” 操作符,以及提供一个静态的创建和销毁方法。但是对每个类都写这些雷同的代码是本座不能容忍的,因此,本座使用宏把整个 Singleton 模式封装起来,无论是类的定义还是类的使用的极其简单,请看代码:

 

/******************************************************************************
Module: Singleton.h
Notices: Copyright (c) 2006 Bruce Liang
Purpose: 用于简化 Singleton 模式的定义.
Desc:
*****************************************************************************
*/

#pragma once

#define SINGLETON_THIS(ClassName) ClassName::GetThis()
#define SINGLETON_INSTANCE(ClassName) ClassName::GetInstance()
#define SINGLETON_OBJECT(ObjName) SINGLETON_INSTANCE(C##ObjName)

#define DEFINE_SINGLETON(ClassName) \
ClassName* ClassName::m_pThis = NULL;

#define DEFINE_P_THIS(ClassName) \
DEFINE_SINGLETON(ClassName)

#define DECLARE_SINGLETON_INTERFACE(ClassName) \
public: \
static ClassName* GetThis() {return m_pThis;} \
static ClassName& GetInstance() {return *m_pThis;} \
protected: \
static ClassName* m_pThis;

#define DECLARE_SINGLETON_CREATE_INSTANCE(ClassName) \
public: \
static BOOL CreateInstance() \
{ \
if(!m_pThis) \
m_pThis = new ClassName; \
\
return m_pThis != NULL; \
} \
\
static BOOL DeleteInstance() \
{ \
if(m_pThis) \
{ \
delete m_pThis; \
m_pThis = NULL; \
} \
\
return m_pThis == NULL; \
}

#define DECLARE_PRIVATE_DEFAULT_CONSTRUCTOR(ClassName) \
private: \
ClassName(){}

#define DECLARE_PRIVATE_COPY_CONSTRUCTOR(ClassName) \
private: \
ClassName(const ClassName&); \
ClassName& operator = (const ClassName&);

#define DECLARE_NO_COPY_CLASS(className) \
DECLARE_PRIVATE_COPY_CONSTRUCTOR(className)


#define DECLARE_SINGLETON_IMPLEMENT_NO_CREATE_INSTANCE(ClassName) \
DECLARE_SINGLETON_INTERFACE(ClassName) \
DECLARE_PRIVATE_DEFAULT_CONSTRUCTOR(ClassName) \
DECLARE_PRIVATE_COPY_CONSTRUCTOR(ClassName)

#define DECLARE_SINGLETON_IMPLEMENT_NO_DEFAULT_CONSTRUCTOR(ClassName) \
DECLARE_SINGLETON_CREATE_INSTANCE(ClassName) \
DECLARE_PRIVATE_COPY_CONSTRUCTOR(ClassName)

#define DECLARE_SINGLETON_IMPLEMENT(ClassName) \
DECLARE_SINGLETON_IMPLEMENT_NO_DEFAULT_CONSTRUCTOR(ClassName) \
DECLARE_PRIVATE_DEFAULT_CONSTRUCTOR(ClassName)

#define DECLARE_SINGLETON_NO_DEFAULT_CONSTRUCTOR(ClassName) \
DECLARE_SINGLETON_INTERFACE(ClassName) \
DECLARE_SINGLETON_IMPLEMENT_NO_DEFAULT_CONSTRUCTOR(ClassName)

#define DECLARE_SINGLETON(ClassName) \
DECLARE_SINGLETON_NO_DEFAULT_CONSTRUCTOR(ClassName) \
DECLARE_PRIVATE_DEFAULT_CONSTRUCTOR(ClassName)


template<class T>
class CSingleObject
{
public:
CSingleObject () {T::CreateInstance();}
~CSingleObject () {T::DeleteInstance();}
T* GetPointer () {return T::GetThis();}
T& GetObject () {return T::GetInstance();}
BOOL IsValid () {return GetPointer() != NULL;}
};
 #define DECLARE_SINGLE_OBJECT(ClassName) CSingleObject<ClassName> _##ClassName##_Single_Object_;

 

  • Singleton 类头文件(MyClass.h
#pragma once

#include "../Common/Src/Singleton.h"

// 为使用方便,定义‘MyClass’代替‘CMyClass::GetInstance()’
#define MyClass SINGLETON_INSTANCE(CMyClass)

class CMyClass
{
private:
int x;
int y;

public:
int mix();

private:
// 自定义构造函数(可选,一般情况下不需要自定义构造函数)
CMyClass() : x(123), y(456) {}

/***** 声明 Singleton *****/

// 如果上面没有自定义构造函数,Singleton 声明为:
// DECLARE_SINGLETON(CMyClass)
// 否则声明为:
DECLARE_SINGLETON_NO_DEFAULT_CONSTRUCTOR(CMyClass)
};

 

  • Singleton 类实现文件(MyClass.cpp
#include "StdAfx.h"
#include "MyClass.h"

// 声明:CMyClass* CMyClass::m_pThis
DEFINE_SINGLETON(CMyClass)

int CMyClass::mix()
{
return x * y;
}

 

  • 使用方式
#include "stdafx.h"
#include "MyClass.h"

// 用 CMyClass::CreateInstance() 创建唯一实例
DECLARE_SINGLE_OBJECT(CMyClass)

int _tmain(int argc, _TCHAR* argv[])
{
// 访问唯一实例
int result = MyClass.mix();

std::cout << result << endl;

return 0;
}

 

posted on 2012-02-12 22:14  ~怪^_*兽~  阅读(4673)  评论(18编辑  收藏