为了学习C++中的OOP,我想用工厂设计模式创建一个ToolFactory。
但我不知道我必须如何开发它。但我曾尝试开发它,但它不起作用。
您可以在下面找到我为创建 ToolFactory 编写的所有代码,这些代码可以创建带有 vector 的工具箱。
我希望我的问题能说清楚。
类:
勤杂工.hpp :#ifndef BRICOLEUR_HPP
#define BRICOLEUR_HPP
#include <ScrewDriver.hpp>
#include <Saw.hpp>
#include <Hammer.hpp>
#include <string>
class Handyman
{
public:
void screw(ScrewDriver t){t.screw();}
void cut(Saw s){s.cut();}
void crack(Hammer m){m.crack();}
};
#endif
锤子.hpp :
#ifndef MARTEAU_HPP
#define MARTEAU_HPP
#include <iostream>
#include <Tool.hpp>
#include <ToolBreak.hpp>
class Hammer : public Tool, ToolBreak
{
std::string nom;
public:
Hammer(std::string const & nom){this->nom = nom;}
std::string get_nom(){return this->nom;}
void crack(){std::cout << "Hammer crack" << std::endl;}
~Hammer();
};
#endif
锯.hpp :
....
#include <ToolCutting.hpp>
class Saw : public Tool, ToolCutting
{
....
public:
....
void cut(){std::cout << "Saw cut" << std::endl;}
....
};
#endif
Screwdriver .hpp :
....
#include <ToolScrewing.hpp>
class ScrewDriver : public Tool, ToolScrewing
{
....
public:
....
void screw(){std::cout << "ScrewDriver screw" << std::endl;}
....
};
#endif
界面
工具断点.hpp#ifndef TOOLBREAK_HPP
#define TOOLBREAK_HPP
#include <string>
class ToolBreak
{
public:
virtual std::string get_nom() = 0;
virtual void crack() = 0;
};
#endif
界面相同模型:
- 刀具切割.hpp
- 工具螺丝.hpp
工厂
工具工厂.hpp#ifndef TOOLFACTORY_HPP
#define TOOLFACTORY_HPP
#include <memory>
#include <Tool.hpp>
#include <ScrewDriver.hpp>
#include <Hammer.hpp>
#include <Saw.hpp>
class ToolFactory
{
public:
static Tool create (std::string name, std::string arg);
};
#endif
工具工厂.cpp
#include <ToolFactory.hpp>
Tool ToolFactory::create(std::string name, std::string args)
{
if(name.compare("Screwdriver") == 0)
{
return ScrewDriver(args);
}
else if(name.compare("Hammer") == 0)
{
return Hammer(args);
}
else if(name.compare("Saw") == 0)
{
return Saw(args);
}
else
{
std::cout << "Error ! Tool not found" << std::endl;
}
}
main.cpp
#include <vector>
#include <Handyman.hpp>
#include <ToolFactory.hpp>
using namespace std;
int main()
{
Handyman handy;
ScrewDriver screwdriver("Blue screwdriver");
Saw saw("Green saw");
Hammer hammer("Yellow hammer");
handy.screw(screwdriver);
handy.cut(saw);
handy.crack(hammer);
Tool screwdriverV2 = ToolFactory::create("Screwdriver", "Screwdriver v2");
screwdriverV2.display();
return 0;
}
输出
clang++ -Wall -std=c++14 -c -o obj/main.o src/main.cpp -I include
clang++ -Wall -std=c++14 -c -o obj/Handyman.o src/Handyman.cpp -I include
clang++ -Wall -std=c++14 -c -o obj/Saw.o src/Saw.cpp -I include
clang++ -Wall -std=c++14 -c -o obj/ScrewDriver.o src/ScrewDriver.cpp -I include
clang++ -Wall -std=c++14 -c -o obj/Hammer.o src/Hammer.cpp -I include
clang++ -Wall -std=c++14 -c -o obj/Tool.o src/Tool.cpp -I include
clang++ -Wall -std=c++14 -c -o obj/ToolScrewing.o src/ToolScrewing.cpp -I include
clang++ -Wall -std=c++14 -c -o obj/ToolBreak.o src/ToolBreak.cpp -I include
clang++ -Wall -std=c++14 -c -o obj/ToolCutting.o src/ToolCutting.cpp -I include
clang++ -Wall -std=c++14 -c -o obj/ToolFactory.o src/ToolFactory.cpp -I include
src/ToolFactory.cpp:21:1: warning: control may reach end of non-void function [-Wreturn-type]
}
^
1 warning generated.
clang++ -Wall -std=c++14 -o bin/main obj/main.o obj/Handyman.o obj/Saw.o obj/ScrewDriver.o obj/Hammer.o obj/Tool.o obj/ToolScrewing.o obj/ToolBreak.o obj/ToolCutting.o obj/ToolFactory.o
./bin/main
ScrewDriver screw
Saw cut
Hammer crack
It's a tool
最佳答案
要保持对象类型,您需要通过指针而不是值来传递它,否则您将遇到对象切片问题。当您在创建时传递对象所有权时,您应该使用智能指针:
class ToolFactory
{
public:
static std::unique_ptr<Tool> create (std::string name, std::string arg);
};
std::unique_ptr<Tool> ToolFactory::create(std::string name, std::string args)
{
if(name.compare("Screwdriver") == 0)
{
return std::make_unique<ScrewDriver>(args);
}
// note as your if has return statement you do not really need else
...
}
下一步可能是用 std::unordered_map
消除级联 if
:
class ToolFactory
{
using Creator = std::function<std::unique_ptr<Tool>(std::string)>
using Creators = std::unordered_map<std::string,Creator>;
Creators m_creators;
public:
ToolFactory();
std::unique_ptr<Tool> create (std::string name, std::string arg);
};
ToolFactory::ToolFactory()
{
m_creators[ "Screwdriver" ] = []( std::string arg ) { return std::make_unique<ScrewDriver>(arg); }
...
}
std::unique_ptr<Tool> ToolFactory::create (std::string name, std::string arg)
{
auto f = m_creators.find( name );
if( f == m_creators.end() )
throw std::runtime_error( "unknown type:" + name );
return f->second( arg );
}
这样它不仅会更通用,而且您可以轻松地扩展它以动态添加新类型。
关于c++ - C++中如何实现工厂设计模式?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/54830073/