Question

如何在课堂上初始化std::map变量。

当前我的代码未编译，并且出现错误。

Error   C3376   'SumCommandInterface::call_function': only static data member templates are allowed

代码：

class SumCommandInterface
{

private:
    std::string stdstrCommand;
    std::map < std::string, PluginTypeLookUp > lookUpPluginMap;

 // I want to initialize this member
    template<typename plugin>
    std::map<std::string, std::function<void(plugin* plug, const std::string &, const std::string &)>> call_function;

public:
    SumCommandInterface();  
    int receiveCommand(std::string stdtsrCommand , const QModelIndex & RootIndex , TreeModel *myModel);
    bool getTreeItem(const std::string &stdstrName , const QModelIndex & RootIndex, TreeModel *myModel , TreeItem** item );
    template<typename plugin, typename fieldType>
    inline void setFontPluginParam(plugin* geom, std::string paramName, fieldType val);

    template<typename plugin, typename fieldType>
    inline void setTexturePluginParam(plugin* geom, std::string paramName, fieldType val);

    template<typename plugin>
    void stringFunction(plugin* plug , const std::string& name, std::string stdstr);

    template<typename plugin>
    void intFunction( plugin* plug, const std::string& name, std::string stdstr);

    template<typename plugin>
    void floatFunction(plugin* plug , const std::string& name, std::string stdstr);

    template<typename plugin>
    void boolFunction(plugin* plug , const std::string& name, std::string stdstr);

};


template<typename plugin, typename fieldType>
inline void SumCommandInterface::setTexturePluginParam(plugin* plug, std::string paramName, fieldType val)
{
    CommandInterfaceTexture commandInterface;
    Sum_Texture_2D *texture = plug;
    commandInterface.SetValue< Sum_Texture_2D >(texture, paramName, val);
}

template<typename plugin>
void SumCommandInterface::stringFunction(plugin* plug, const std::string& name, std::string stdstr)
{
    setFontPluginParam<Geometry , std::string>(plug, name , stdstr)
}

template<typename plugin>
void SumCommandInterface::intFunction(plugin* plug, const std::string& name, std::string stdstr )
{
    setFontPluginParam<Geometry, std::string>(plug, name, std::stoi(stdstr));
}

template<typename plugin>
void SumCommandInterface::floatFunction(plugin* plug, const std::string& name, std::string stdstr)
{
    setFontPluginParam<Geometry, std::string>(plug, name, std::stof(stdstr));
}

template<typename plugin>
void SumCommandInterface::boolFunction(plugin* plug, const std::string& name, std::string stdstr)
{
    setFontPluginParam<Geometry, std::string>(plug, name, (stdstr == '0' ? false : true ));
}

这应该是定义

template<typename plugin>
std::map<std::string, std::function<void(plugin* plug, const std::string &, const std::string &)>> call_function =
{
    {"TEXT", SumCommandInterface::stringFunction },
    {"USESHADOW", SumCommandInterface::boolFunction },
    {"FONTSIZE", SumCommandInterface::intFunction },
    {"SHADOWDISTANCE", SumCommandInterface::floatFunction },
    {"SHADOWOPACITY", SumCommandInterface::floatFunction },
    {"KERNING", SumCommandInterface::floatFunction }
};

Answer 1

好，现在我看到了问题。

它应该像这样：

// template<typename plugin> // this is problem too - see below!
std::map<std::string, std::function<void(plugin* plug, const std::string &, const std::string &)>> call_function =
{
    {
        "TEXT",
        [this](plugin* plug, const std::string &s, const std::string &s2)
        {
            SumCommandInterface::stringFunction(plug, s1, s2); };
        }
    },
    {
        "USESHADOW",
        ...
    },
};

请注意std::function，您必须提供与std::function内的声明和您的SumCommandInterface::stringFunction要求的隐式参数this相匹配的函数（为特定对象调用常规方法）。 / p>

因此，作为解决方案，我使用了lambda表达式来捕获丢失的this。

模板也有问题。您不能将类字段声明为模板。只有方法可以是模板，整个类都可以是模板，而不是字段。

这里仅是最小的完整示例说明了它的工作原理：https://wandbox.org/permlink/PAMGV04fr0BN4ueb 我无法快速修复您的代码。

如何将std :: map初始化为类成员

1 个答案: