抽象工厂 - 获取 LKN2019 死亡错误消息答案

【问题标题】：Abstract Factory - getting LKN2019 of death error message抽象工厂 - 获取 LKN2019 死亡错误消息
【发布时间】：2013-04-14 19:54:04
【问题描述】：

我知道我一定遗漏了一个你似乎无法发现的细节，然后在一个月后它击中你“Evrika！”。

基本上，我要做的是为形状实现一个抽象工厂类，但我不断收到与我的形状工厂代码创建的 .obj 相关的 LKN2019 错误消息。

看起来有点像这样：

shapefactory.h

#ifndef SHAPEFACTORY_H__
#define SHAPEFACTORY_H__

#include <iostream>
#include <map>
#include <string>
#include "shape.h"
#include "circle.h"
#include "rectangle.h"
#include "triangle.h"

using namespace std;

typedef Shape *(createShapeFunction)(void);




class ShapeFactory
{
public:
    static void registerFunction(const string &, const createShapeFunction *);
    static Shape *createShape(const string &);
    static Shape *createShape(istream &);
private:
    static map <string, createShapeFunction *> creationFunctions;
    ShapeFactory();
    static ShapeFactory *getShapeFactory();
};




#endif

shapefactory.cpp

    #include "shapefactory.h"





void ShapeFactory::registerFunction(const string & ID, const crateShapeFunction * CR )
{
    creationFunctions[ID] = CR;
}




Shape* ShapeFactory::createShape(const string & shapeName)
{
    map <string, crateShapeFunction *>::iterator it = creationFunctions.find(shapeName);
    if( it != creationFunctions.end() )
        return it->second();
    return NULL;

}


Shape* ShapeFactory::createShape(istream & in)
{
    string shapeName;
    cout << "Desired figure: ";
    in >> shapeName;

    map <string, crateShapeFunction *>::iterator it = creationFunctions.find(shapeName);
    if( it != creationFunctions.end() )
        return it->second();

    return NULL;

}



ShapeFactory::ShapeFactory()
{

    registerFunction("circle", &Circle::Create);
    registerFunction("rectangle", &Rectangle::Create);
    registerFunction("triangle", &Triangle::Create);

}



ShapeFactory* ShapeFactory::getShapeFactory()
{
    static ShapeFactory instance;
    return &instance;
}

我可能在方法实现的某个地方搞砸了，但我根本看不到在哪里。任何形式的及时帮助将不胜感激。

编辑：错误看起来像这样

错误 4 错误 LNK2001: unresolved external symbol "private: static class std::map,class std::allocator >,class Shape * (__cdecl*)(void),struct std::less,class std::allocator > >,class std::allocator,class std::allocator > const ,class Shape * (__cdecl*)(void)> > > ShapeFactory::creationFunctions" (?creationFunctions@ShapeFactory@@0V?$map@V?$ basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@P6APAVShape@@XZU?$less@V?$basic_string@DU?$char_traits@D@std@@V? $allocator@D@2@@std@@@2@V?$allocator@U?$pair@$$CBV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@ @std@@P6APAVShape@@XZ@std@@@2@@std@@A) C:\Proj1\shapefactory.obj

在按照 alexrider 的建议在我的标题中定义地图之前。谢谢 - 现在可以使用了。

【问题讨论】：

请包含完整错误消息。 “LKN2019”只是您收到的消息的一部分。
在头文件中使用using namespace std; 可能很快就会大吃一惊。

标签： c++ linker factory

【解决方案1】：

您缺少static map <string, createShapeFunction *> creationFunctions;的定义
这可以通过添加

来解决

map <string, createShapeFunction *> ShapeFactory::creationFunctions;

进入 shapefactory.cpp
顺便说一句，粘贴您收到的实际错误消息会很有帮助。

【讨论】：