C语言实现

/*************************************************************************
    > File Name: prototype.c
    > Author: XXDK
    > Email: [email protected] 
    > Created Time: Mon 10 Sep 2018 05:52:03 PM CST
 ************************************************************************/

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<assert.h>

typedef struct _Data
{
    struct _Data* (*copy) (struct _Data* pData);
    int data;
}Data;

Data* data_copy_A(Data* pData)
{
    Data* pResult = (Data*)malloc(sizeof(Data));
    assert(NULL != pResult);
    memmove(pResult, pData, sizeof(Data));

    return pResult;
}

Data data_A = {
    data_copy_A, 
    2
};

Data* clone(Data* pData)
{
    return pData->copy(pData);
}

int main()
{
    Data* data_B = clone(&data_A);
    printf("Data.data = %d\n", data_B->data);

    return 0;
}

C++实现

/*************************************************************************
    > File Name: prototype.cpp
    > Author: XXDK
    > Email: [email protected] 
    > Created Time: Mon 10 Sep 2018 05:28:17 PM CST
 ************************************************************************/

#include<iostream>
using namespace std;

class Data
{
public:
    Data() {}
    virtual ~Data() {}
    virtual Data* copy() = 0;
};

class DataA : public Data
{
public:
    DataA() {}
    virtual ~DataA() {}
    Data* copy() override {
        std::cout << typeid(DataA).name()<<"::" << __func__<< std::endl;
        return new DataA();
    }
};

class DataB : public Data
{
public:
    DataB() {}
    virtual ~DataB() {}
    Data* copy() override {
        std::cout << typeid(DataB).name() << "::"<<__func__ << std::endl;
        return new DataB();
    }
};

Data* clone(Data* pData)
{
    return pData->copy();
}

int main()
{
    Data* pa = new DataA();
    Data* p1 = clone(pa);

    Data* pb = new DataB();
    Data* p2 = clone(pb);

    delete pa, pb, p1, p2;
}