本文介紹設計模式中的原型模式。

本質上其實就是克隆。

下面以個人簡歷為例進行舉例說明：

深拷貝版本：

#include <iostream>
#include <string>
#include <memory>

using namespace std;

template<class T>
class ICloneable
{
public:
	virtual T* clone() = 0;
};

class CWorkExperience
{
public:
	CWorkExperience(){}

	CWorkExperience(const string& company,
		const string& workTime)
	{
		m_strCompany = company;
		m_strWorkTime = workTime;
	}

	CWorkExperience(const CWorkExperience& right)
	{
		m_strCompany = right.m_strCompany;
		m_strWorkTime = right.m_strWorkTime;
	}

	~CWorkExperience()
	{
		cout << "CWorkExperience析構" << endl;
		printInfo();
	}

	void setCompany(const string& company)
	{
		m_strCompany = company;
	}

	const string& getCompany() const
	{
		return m_strCompany;
	}

	void setWorkTime(const string& workTime)
	{
		m_strWorkTime = workTime;
	}

	const string& getWorkTime() const
	{
		return m_strWorkTime;
	}

	void printInfo()
	{
		cout << "Company: " << m_strCompany << endl;
		cout << "WorkTime: " << m_strWorkTime << endl;
	}

private:
	string m_strCompany;		// company name
	string m_strWorkTime;		// work time
};

// 簡歷類
class CResume : public ICloneable<CResume>
{
public:
	CResume(){}
	~CResume()
	{
		cout << "CResume析構 " << m_name << endl;
	}

	void setInfo(const string& name, const string& sex
		, int age)
	{
		m_name = name;
		m_sex = sex;
		m_age = age;
	}

	void setExperience(const string& company, const string& workTime)
	{
		m_experience.setCompany(company);
		m_experience.setWorkTime(workTime);
	}

	CResume* clone()
	{
		CResume* resume = new CResume;
		resume->setInfo(m_name, m_sex, m_age);
		resume->setExperience(m_experience.getCompany(), m_experience.getWorkTime());
		return resume;
	}

	void printInfo()
	{
		cout << "Name: " << m_name << endl;
		cout << "Sex: " << m_sex << endl;
		cout << "Age: " << m_age << endl;
		cout << "Experience: " << endl;
		m_experience.printInfo();
		cout << endl;
	}
protected:
	string m_name;
	string m_sex;
	int m_age;

	CWorkExperience m_experience;// 物件
};

void testPrototype()
{
	CResume re;
	re.setInfo("Jacky", "Male", 20);
	re.setExperience("MS", "2001.11 - 2005.11");
	re.printInfo();

	CResume* pClone = re.clone();
	pClone->setInfo("Marry", "Female", 30);
	pClone->setExperience("Google", "2006.01 - 2010.01");
	pClone->printInfo();

	delete pClone;
	pClone = NULL;
}

int main(void)
{
	testPrototype();

	return 0;
}
 

執行結果如下：

#include <iostream>
#include <string>
#include <memory>

using namespace std;

// 克隆介面
template<class T>
class ICloneable
{
public:
	virtual T* clone() = 0;
};

// 工作經歷類
class CWorkExperience
{
public:
	CWorkExperience(){}

	CWorkExperience(const string& company,
		const string& workTime)
	{
		m_strCompany = company;
		m_strWorkTime = workTime;
	}

	CWorkExperience(const CWorkExperience& right)
	{
		m_strCompany = right.m_strCompany;
		m_strWorkTime = right.m_strWorkTime;
	}

	~CWorkExperience()
	{
		cout << "CWorkExperience析構" << endl;
		printInfo();
	}

	void setCompany(const string& company)
	{
		m_strCompany = company;
	}

	const string& getCompany() const
	{
		return m_strCompany;
	}

	void setWorkTime(const string& workTime)
	{
		m_strWorkTime = workTime;
	}

	const string& getWorkTime() const
	{
		return m_strWorkTime;
	}

	void printInfo()
	{
		cout << "Company: " << m_strCompany << endl;
		cout << "WorkTime: " << m_strWorkTime << endl;
	}

private:
	string m_strCompany;		// company name
	string m_strWorkTime;		// work time
};

// 簡歷類
class CResume : public ICloneable<CResume>
{
private:
	// 只允許呼叫帶引數的建構函式和拷貝建構函式
	CResume(){m_experience = NULL;}
public:
	// 帶參建構函式
	CResume(CWorkExperience* pWorkExperience)
	{
		// 不負責記憶體分配 只是共享
		m_experience = pWorkExperience;
	}

	// 帶參拷貝建構函式
	CResume(const CResume& right)
	{
		m_name = right.m_name;
		m_sex = right.m_sex;
		m_age = right.m_age;
		// 注意這裡是指標賦值 屬於淺拷貝
		m_experience = right.m_experience;
	}

	~CResume()
	{
		cout << "CResume析構 " << m_name << endl;
	}

	void setInfo(const string& name, const string& sex
		, int age)
	{
		m_name = name;
		m_sex = sex;
		m_age = age;
	}

	void setExperience(const string& company, const string& workTime)
	{
		m_experience->setCompany(company);
		m_experience->setWorkTime(workTime);
	}

	CResume* clone()
	{
		// 呼叫拷貝建構函式 淺拷貝
		CResume* resume = new CResume(*this);
		return resume;
	}

	void printInfo()
	{
		cout << "Name: " << m_name << endl;
		cout << "Sex: " << m_sex << endl;
		cout << "Age: " << m_age << endl;
		cout << "Experience: " << endl;
		m_experience->printInfo();
		cout << endl;
	}
protected:
	string m_name;
	string m_sex;
	int m_age;

	CWorkExperience* m_experience;// 指標 聚合
};

void testPrototype()
{
	CWorkExperience* pWorkExperience = new CWorkExperience("MS", "2001.11 - 2005.11");
	CResume re(pWorkExperience);	// 只能這樣構造 無參構造被遮蔽掉了
	re.setInfo("Jacky", "Male", 20);
	re.printInfo();

	CResume* pClone = re.clone();	// 指標賦值 淺拷貝
	//delete pWorkExperience;		// 這裡如果呼叫delete 程式會崩潰(因為是共享)

	pClone->setInfo("Marry", "Female", 30);
	pClone->setExperience("Google", "2006.01 - 2010.01");
	pClone->printInfo();

	re.printInfo();	// 我們發現原物件的workExperience屬性已經被修改

	delete pClone;
	delete pWorkExperience;
	pClone = NULL;
	pWorkExperience = NULL;
}

int main(void)
{
	testPrototype();

	return 0;
}
 

執行結果如下：

將146行取消註釋 程式崩潰。

執行圖如下：(圖片請在新視窗中檢視)

接下來一篇文章解決指標共享的深度拷貝版本。