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HerrAskin
Asked:2023-12-08 21:13:46 +0000 UTC2023-12-08 21:13:46 +0000 UTC

实心+浸镀+工厂

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同事们，一个关于接口、依赖倒置、创建类实例的问题。假设有一个“客户端”（main.cpp）需要一些数据。客户并不关心他如何接收它们：从内存，从文件，通过网络......他只使用界面，即

数据存储.hpp

struct Data
{
    int a = 0;
    int b = 0;
    int c = 0;
};

// интерфейс
class DataStorage
{
public:
    virtual ~DataStorage() {};
    virtual Data getData() = 0;
};

主程序

#include <iostream>
#include "dataStorage.hpp"

using namespace std;

int main()
{
    DataStorage* dataStorage;

    Data data = dataStorage->getData();

    cout << "a = " << data.a << '\t' << "b = " << data.b << '\t' << "c = " << data.c << '\n';
    return 0;
}

接口实现：

数据存储Imp.hpp

class DataFromMemory: public DataStorage
{
public:
    DataFromMemory();
    Data getData() override;
};


class DataFromFile: public DataStorage
{
public:
    DataFromFile();
    Data getData() override;
};

数据存储Imp.cpp

#include "dataStorageImp.hpp"


DataFromMemory::DataFromMemory() {};

Data DataFromMemory::getData()
{
    Data data;
    data.a = 1;
    data.b = 2;
    data.c = 3;
    return data;
}


DataFromFile::DataFromFile() {};

Data DataFromFile::getData()
{
    Data data;
    data.a = 10;
    data.b = 20;
    data.c = 30;
    return data;
}

代码不起作用，就像一片空白。事实上，问题是我应该如何以及在哪里创建实现类的实例DataFromMemory和DataFomFile？可以通过条件if "fromFile": {}or进行选择if "from_memory": {}，或者使用宏#define USE_MEMORYor进行选择USE_FILE。不重要。

c++

1 个回答

  1. Best Answer

    我做了以下实现。C++ 和 SOLID 专家请发表评论。

    “主.cpp”

    #define USE_DATA_FROM_MEMORY
//#define USE_DATA_FROM_FILE

#include <iostream>
#include "creator.hpp"

using namespace std;

int main()
{
    Creator* creator;
    DataStorage* dataStorage = creator->getInstance();

    Data data = dataStorage->getData();

    cout << "a = " << data.a << '\t' << "b = " << data.b << '\t' << "c = " << data.c << '\n';

    delete dataStorage;
    dataStorage = nullptr;

    return 0;
}

    “创建者.hpp”

    #ifndef CREATOR_HPP
#define CREATOR_HPP

#include "dataStorageImp.hpp"

class Creator
{
public:
    DataStorage* getInstance()
    {
        #ifdef USE_DATA_FROM_MEMORY
        return new DataFromMemory();
        #endif // USE_DATA_FROM_MEMORY

        #ifdef USE_DATA_FROM_FILE
        return new DataFromFile();
        #endif // USE_DATA_FROM_FILE
    };
    ~Creator() = default;
};

#endif // CREATOR_HPP

    “数据存储.hpp”

    #ifndef DATASTORAGE_HPP
#define DATASTORAGE_HPP

struct Data
{
    int a = 0;
    int b = 0;
    int c = 0;
};


class DataStorage
{
public:
    virtual Data getData() = 0;
    virtual ~DataStorage() {};
};

#endif // DATASTORAGE_HPP

    “数据存储Imp.hpp”

    #ifndef DATASTORAGEIMP_HPP
#define DATASTORAGEIMP_HPP

#include "dataStorage.hpp"

// это просто некая реализация
class DataFromMemory: public DataStorage
{
public:
    DataFromMemory() = default;
    Data getData() override
    {
        Data data;
        data.a = 1;
        data.b = 2;
        data.c = 3;
        return data;
    }
};

// другая реализация, другие значения
class DataFromFile: public DataStorage
{
public:
    DataFromFile() = default;
    Data getData() override
    {
        Data data;
        data.a = 10;
        data.b = 20;
        data.c = 30;
        return data;
    }
};

#endif // DATASTORAGEIMP_HPP

    再次强调，客户端 (main.cpp) 只通过接口接收数据，无论数据来源如何。这个问题纯粹是理论上的，需要您自己了解如何做到这一点。

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