C++ 包括类命名空间和类实例化

Question

我一直在编写一些代码来尝试为某种出租车服务建模，但我遇到了一些问题。

我有一个类RunServer，它查看用户给出的命令的状态（src::control::Global::stat_commandPath）并要求额外的输入基于这些命令，然后再使用该输入进行操作。

问题是我得到一个“错误：预期的类型说明符”（GCC-7.3.0，C++11），它看起来可能与我如何命名类有关.如果从 src/Vehicle/Car.h 中删除 namespace 声明，则此问题不再发生。

这应该是这个问题的所有相关代码。抱歉，内容太多了，我已经截断了所有看起来没有影响的内容。问题在于 src/control/RunServer.h 第 66、70 和 74 行。src/vehicle/Pickup.h 和 src/vehicle/Van。 h 与 src/vehicle/Car.h 具有相同的结构。

src/control/Global.h

#ifndef INCLUDED_src_control_Global_h
#define INCLUDED_src_control_Global_h

#include <string>

#include "../vehicle/Vehicle.h"


namespace src {
namespace control {


    class Global final
    {
        virtual void instantiable() = 0;

        private:

            static size_t
                stat_vehicleArrayLength;

            static src::Vehicle
            ** stat_vehicleArray;

        public:

            static std::string
                stat_commandPath,
                stat_stdcoutEnd;

        public:

            static bool
                // Deletes the pointer argument if adding fails.
                add_vehicle(
                    src::Vehicle *
                ),
                exists_vehicle(
                    std::string
                ),
                remove_vehicle(
                    std::string
                );

            static size_t
                get_vehicleAmount(),
                position_vehicle(
                    std::string
                );

            static src::Vehicle
            ** get_vehicles();
    };


}}


#endif

src/control/RunServer.cpp

#include <iostream>
#include <stdlib.h>  // exit()
#include <string>
#include <regex>

#include "../../lib/StringTools.h"
#include "../vehicle/Car.h"
#include "../vehicle/Pickup.h"
#include "../vehicle/Van.h"
#include "../vehicle/VehicleType.h"
#include "../person/Driver.h"
#include "../person/Passenger.h"
#include "Global.h"
#include "RunServer.h"


inline bool
src::control::RunServer::navigation(
    std::string input)
{
    if (input == "return")
    {
        src::control::Global::stat_commandPath.pop_back();
        return true;
    }
    if (input == "exit")
    {
        exit(0);
        return true;
    }
    return false;
}

void
src::control::RunServer::run()
{
    std::string input;

    // "0"   ~ Create...
    // "00"  ~ Create > Vehicle...
    // "000" ~ Create > Vehicle > Car
    // "001" ~ Create > Vehicle > Pickup
    // "002" ~ Create > Vehicle > Van
    // "01"  ~ Create > Person...
    // "010" ~ Create > Person > Driver
    // "011" ~ Create > Person > Passenger
    // "1"   ~ Destroy...
    // "10"  ~ Destroy > Vehicle
    // "11"  ~ Destroy > Passenger
    // "2"   ~ Print

    if (src::control::Global::stat_commandPath == "000" || src::control::Global::stat_commandPath == "001" || src::control::Global::stat_commandPath == "002")
    {
        // Create > Vehicle > (Car|Pickup|Van).
        std::cout << "\n";
        std::cout << "<vehicle identification (char array)>" << src::control::Global::stat_stdcoutEnd;
        getline(std::cin, input);

        if (src::control::RunServer::navigation(input))
        {
            return;
        }

        if (std::regex_match(input, std::regex("\\w+")))
        {
            if (src::control::Global::stat_commandPath.back() == '0' && !src::control::Global::add_vehicle(new src::vehicle::Car(input)))
            {
                std::cout << "\nA vehicle with this identifier already exists!\n";
            }
            else if (src::control::Global::stat_commandPath.back() == '1' && !src::control::Global::add_vehicle(new src::vehicle::Pickup(input)))
            {
                std::cout << "\nA vehicle with this identifier already exists!\n";
            }
            else if (src::control::Global::stat_commandPath.back() == '2' && !src::control::Global::add_vehicle(new src::vehicle::Van(input)))
            {
                std::cout << "\nA vehicle with this identifier already exists!\n";
            }
            else
            {
                std::cout << "\nAn error occured!\n";
            }
        }
    }
}

src/vehicle/Car.h

#ifndef INCLUDED_src_vehicle_Car_h
#define INCLUDED_src_vehicle_Car_h

#include <string>

#include "Vehicle.h"


namespace src {
namespace vehicle {


    class Car final : public src::Vehicle
    {
        void instantiable() override {};

        public:

            Car();
            Car(
                std::string
            );

            int
                canAddPassenger(
                    src::person::Passenger *
                ) override;
    };


}}


#endif

Answer 1

问题似乎与案例有关。似乎命名空间查找不区分大小写，而命名空间声明是。将src::vehicle::Car 的命名空间更改为src::avehicle::Car 解决了这个问题。

Answer 2

这是完全错误的：

        static bool
            // Deletes the pointer argument if adding fails.
            add_vehicle(
                src::Vehicle *
            ),
            exists_vehicle(
                std::string
            ),
            remove_vehicle(
                std::string
            );

你想在这里完成什么？这不应该是3个独立的原型吗？

        static bool
            // Deletes the pointer argument if adding fails.
            add_vehicle(
                src::Vehicle *
            );
        static bool exists_vehicle(
                std::string
            );
        static bool remove_vehicle(
                std::string
            );