这种情况下虚函数能使用模板代替吗？

有两个 A、B 两个抽象类分别派生出几个类，我想在一类中加一个指针指向另一类的实例。大致代码如下：

class parentA {
public:
    virtual void func() = 0;

    parentB* ptrToAnother; // here
};

class classA1 : public parentA {
public:
    void func() override;
};

class classA2 : public parentA {
public:
    void func() override;
};


class parentB {
public:
    virtual void func() = 0;

    parentA* ptrToAnother; // here
};

class classB1 : public parentB {
public:
    void func() override;
};

class classB2 : public parentB {
public:
    void func() override;
};


classB1 b1;
classA1 a1;
a1.ptrToAnother = &b1;
b1.ptrToAnother = &a1;

a1.ptrToAnother->func();
b1.ptrToAnother->func();

这样就可以通过 ptrToAnother 指针访问另一个类。但是想换成模板实现就爆炸了：

template<typename AnotherClassName>
class parentA {
public:
    virtual void func() = 0;

    AnotherClassName* ptrToAnother; // here
};

template<typename AnotherClassName>
class classA1 : public parentA<AnotherClassName> {
public:
    void func() override;
};

template<typename AnotherClassName>
class classA2 : public parentA<AnotherClassName> {
public:
    void func() override;
};


template<typename AnotherClassName>
class parentB {
public:
    virtual void func() = 0;

    AnotherClassName* ptrToAnother; // here
};

template<typename AnotherClassName>
class classB1 : public parentB<AnotherClassName> {
public:
    void func() override;
};

template<typename AnotherClassName>
class classB2 : public parentB<AnotherClassName> {
public:
    void func() override;
};


// 不能编译，缺少模板参数
classA1<classB1> a1;
classB1<classA1> b1;

a1.ptrToAnother->func();
b1.ptrToAnother->func();