通过singleton模式和global static variable变量做C++程序各个模块之间的数据通信

提示：这个办法可以用在Qt C++程序和Qt QML的数据交换

首次初始化：DDocumentSets::getInstance()->setModel(oa_model);

以后任何class中都可以获得这个实例： DDocumentSet* oa_model = DDocumentSets::getInstance()->getModel();

并调用其方法：  oa_model->xxxx();

header文件：

#ifndef DDOCUMENTSETS_H_#define DDOCUMENTSETS_H_#include "DDocumentSet.hpp"class DDocumentSets {private:static DDocumentSets* _instance;DDocumentSets();DDocumentSet* model;public:    static DDocumentSets* getInstance();    void setModel(DDocumentSet* oa_model);    DDocumentSet* getModel();virtual ~DDocumentSets();};#endif /* DDOCUMENTSETS_H_ */

cpp文件：

#include "DDocumentSets.h"DDocumentSets* DDocumentSets::_instance;//Jiang DDocumentSets* DDocumentSets::getInstance() {if (_instance == 0) {_instance = new DDocumentSets();}return _instance;}void DDocumentSets::setModel(DDocumentSet* model) {this->model = model;}DDocumentSet* DDocumentSets::getModel() {return model;}DDocumentSets::DDocumentSets() {}DDocumentSets::~DDocumentSets() {}

参考：

http://stackoverflow.com/questions/8612206/linker-error-when-using-static-members

在C++程序中，need to define the static variable in cpp file and not in header file.

在Qt程序中，需要在cpp和header文件中都定义相同名字的static变量。否则编译出错：

undefined reference to xxxx(static 变量)