C++ 单例模式

头文件：Singletion.h

 
// 单例模式申明
#define PATTERN_SINGLETON_DECLARE(classname)
public:
static classname* Instance();
static void Close();
private:
static classname* m_pSingletion;

// 单例模式实现
#define PATTERN_SINGLETON_IMPLEMENT(classname)
classname* classname::m_pSingletion = NULL;
	classname* classname::Instance()
{
if (m_pSingletion == NULL)
{
m_pSingletion = new classname;
}
return m_pSingletion;
}
void classname::Close()
{
if (m_pSingletion != NULL)
{
delete m_pSingletion;
m_pSingletion = NULL;
}
}

假设类 sample需要使用单例模式，则在类sample的头文件中声明

#include "Singletion.h"
#define INST_SAMPLE sample::Instance()
class sample
{
	PATTERN_SINGLETON_DECLARE(sample)
public:
	sample();
	~sample();
	//具体的功能 随意
	。。。。。。
}

这样写就相当于是：

#include "Singletion.h"
#define INST_SAMPLE sample::Instance()
class CDSPluginMainUI
{
	public:
	static sample* Instance();
	static void Close();
	private:
	static sample* m_pSingletion;
	
public:
	sample();
	~sample();
}

就是多加了一个 私有成员指针，两个静态函数

在实现的cpp中

#include "sample.h"

PATTERN_SINGLETON_IMPLEMENT(sample)
sample::sample()
{

}

相当于是

sample* sample::m_pSingletion = NULL;

sample* sample::Instance()
{
	if (m_pSingletion == NULL)
	{
		m_pSingletion = new sample;
	}
		return m_pSingletion;
}

void sample::Close()
{
	if (m_pSingletion != NULL)
	{
		delete m_pSingletion;
		m_pSingletion = NULL;
	}
}

完成之后 就可以使用函数Instance()
为了使用方便 我们在头文件中定义

#define INST_SAMPLE sample::Instance()
之后就可以用 INST_SAMPLE 调用这个类了