指向任意类型的std :: vector的指针(或任何其他模板化类) [英] pointer to std::vector of arbitrary type (or any other templated class)

问题描述

让我们说我想要一个指向std :: vector的指针的成员变量，但是我不想指定它存储什么类型的变量.我只想访问独立于其实际泛型类型的那些函数. C ++有可能吗?像这样的东西:

let's say i want to have a member variable for a pointer to std::vector but i do not want to specify what type of variable it stores. I want to access only those functions that are independant of it's actual generic type. is this possible with c++? something like this:

class Foo{
public:
    void setVec(std::vector* someVec){
        myVec = someVec;
    };
    int getSize(){
        return myVec.size();
    };
private:
    std::vector* myVec;
};


int main(){
    Foo foo;
    vector<int> vec1;
    vector<float> vec2;
    foo.setVec(&vec1);
    cout<<foo.getSize();
    foo.setVec(&vec2);
    cout<<foo.getSize();
}

注意:我不想为Foo建立模板，我只想使用具有不同类型的向量的Foo的单个实例.

note: i do not want to template Foo and i want to use only a single instance of Foo with vectors of different type.

当然-如果我可以更改类向量，则可以创建未模板化的基类

of course - if I could alter the class vector then i could create an untemplated baseclass

class Ivector{
    virtual int size()=0;
};

然后创建

class vector<T> : public IVector...

从Ivector继承.但是，如果我无法更改相关类并且模板化类没有这样的非模板化基类，我该怎么办?

inherit from Ivector. but what do I do if i can't alter the class in question and the templated class does not have such an untemplated baseclass?

谢谢！

推荐答案

您几乎可以找到答案.与其让std :: vector从Ivector继承，不如创建一个新类:

You are almost at the answer. Instead of making std::vector inherit from Ivector, create a new class:

template <typename T>
class IVectorImpl : public Ivector
{
public:
    explicit IVectorImpl(std::vector<T> * Data) : m_Data(Data){}
    std::vector<T> * m_Data;
 ...
     virtual int size() const {return m_Data->size();}
  // Implement all the Ivector functions here to call the respective functions off of m_Data
};

现在让您的Foo类保留指向Ivector的指针，而不是std :: vector.

Now have your Foo class keep a pointer to Ivector instead of std::vector.

将Foo :: setVec模板化

Make Foo::setVec templated

template <typename T>
void setVec(std::vector<T> * vec)
{
   Ivector * newVec = new IVectorImpl<T>(vec);
   delete myVec;
   myVec = newVec;
}

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