学习Cocos2dx引擎之CCApplication

###写在开头的话 本人工做是有5，6年了，可是C++也荒废了5.6年，此次从新拿起来忘记了好多东西.有什么地方说的不对的地方请各位高手指点一下.本人很是感谢. ###CCApplication的来源

CCApplication继承自CCApplicationProtocol,这个咱们先无论它,咱们本身写个例子

1.新建CCApplication类

/* * CCApplication.h * * Created on: 2013-9-21 * Author: sjbwybls */

#ifndef CCAPPLICATION_H_

#define CCAPPLICATION_H_

#include <iostream>

#include <string>

namespace TestCocos2dx {

using namespace std;

class CCApplication { public: CCApplication(); virtual ~CCApplication(); int run(); static CCApplication * sharedApplication() { cout<<"return static app"<<endl; return sm_pSharedApplication; }

protected: static CCApplication * sm_pSharedApplication;

};

} /* namespace TestCocos2dx */

#endif /* CCAPPLICATION_H_ */

/* * CCApplication.cpp * * Created on: 2013-9-21 * Author: sjbwybls */

#include "CCApplication.h"

namespace TestCocos2dx {

CCApplication *CCApplication::sm_pSharedApplication = 0;

CCApplication::CCApplication() { cout << "app ctor" << endl; sm_pSharedApplication = this; }

CCApplication::~CCApplication() { cout << "app destroy" << endl; sm_pSharedApplication = NULL; }

int CCApplication::run(){ cout << "run() function, sm_pSharedApplication = " << sm_pSharedApplication << endl; return 0;

}

} /* namespace TestCocos2dx */

2. 新建CCDerivedCCApplication类继承自CCApplication

/* * CCDerivedCCApplication.h * * Created on: 2013-9-21 *
Author: sjbwybls */

#ifndef CCDERIVEDCCAPPLICATION_H_

#define CCDERIVEDCCAPPLICATION_H_

#include <iostream>

#include <string>

#include "CCApplication.h"

namespace TestCocos2dx {

class CCDerivedCCApplication: public TestCocos2dx::CCApplication { public: CCDerivedCCApplication(); virtual ~CCDerivedCCApplication(); };

} /* namespace TestCocos2dx / #endif / CCDERIVEDCCAPPLICATION_H_ */

/* * CCDerivedCCApplication.cpp * * Created on: 2013-9-21 *
Author: sjbwybls */

#include "CCDerivedCCApplication.h"

namespace TestCocos2dx {

using namespace std;

CCDerivedCCApplication::CCDerivedCCApplication() { cout<<"DerivedCCApplication ctor"<<endl;

}

CCDerivedCCApplication::~CCDerivedCCApplication() { cout<<"DerivedCCApplication destory"<<endl; }

} /* namespace TestCocos2dx */

3.最后创建main.cpp

/* * main.cpp * * Created on: 2013-9-21 * Author: sjbwybls */

#include "CCApplication.h"

#include "CCDerivedCCApplication.h"

using namespace TestCocos2dx;

int main() { CCApplication::sharedApplication()->run(); CCDerivedCCApplication app; CCApplication::sharedApplication()->run(); }

4.输出结果 return static app run() function, sm_pSharedApplication = 0 app ctor DerivedCCApplication ctor return static app run() function, sm_pSharedApplication = 0x7fff56b50c20 DerivedCCApplication destory app destroy

5.分析 main.cpp中的实例化了一个CCDerivedCCApplication的实例app。 调用流程： 返回静态父类实体并执行run函数

父类构造函数 子类构造函数 执行run函数 析构子类函数 析构父类函数

6.结论 先从C++的语法说明: C++中静态函数不会触发构造函数 声明一个对象不须要new.便可触发构造函数([具体可参考][1]) 父类跟子类的 构造函数调用关系为 先初始化父类构造函数再初始化子类构造函数 析构函数为 恰好相反 先调用子类析构函数再调用父类析构函数 CCApplication的用法 CCApplication app; //先调用Application必须先初始化Application,也能够从子类调用 CCApplication::sharedApplication()->run(); //最后执行run方法才能拿到初始化以后的Application，负责就只会等到空指针错误，这个也就是Fatal signal 11 (SIGSEGV) at 0x00000000 (code=1)错误出现的缘由吧，但愿高手拍砖

本文启发自:[初学试试看cocos2dx的TestCPP框架(1)][2] [1]:http://www.metsky.com/archives/580.html "声明类实例用new与不用new的区别" [2]:http://blog.csdn.net/hayyoung/article/details/8536719 "初学试试看cocos2dx的TestCPP框架(1)"