Question

I’ve a class with template:

template<class T> class MyClass {
public:
      MyClass() { _genericObj = new T; }
      ~MyClass() { delete _genericObj; }
      void doSomething() { _genericObj.do(); }
private:
      T* _genericObj;
};

And another class:

class AnotherClass {
public:
     AnotherClass(MyClass &obj) { this->_obj = obj; }
     ~AnotherClass() {  }
     doMagic() { _obj->doSomething(); }
private
     MyClass* _obj;
}

Is it right to use in AnotherClass an instance of MyClass without angular parenthesis (for generality)?
If this example is wrong, how can I correct my code? Thank u so much.

Answer 1

You have to decide whether you need a concrete type, by specifying a template parameter for MyClass, or whether you want AnotherClass to be a class template too. You also have the problem that you are passing a reference to some kind of MyClass in the constructor, but you are trying to initialize a pointer to it. The way to fix that really depends on what you want to achieve, these examples assume your AnotherClass will own a dynamically allocated object of type MyClass<SomeType>:

class AnotherClass {
public:
     AnotherClass(MyClass<int> &obj) { this->obj_ = new MyClass<int>(obj); }
     ~AnotherClass() { delete obj_; }
     doMagic() { obj_->doSomething(); }
private
     MyClass<int>* obj_;
}

or

template <typename T>
class AnotherClass {
public:
     AnotherClass(MyClass<T> &obj) { this->obj_ = new MyClass<T>(obj); }
     ~AnotherClass() {  delete obj_;} 
     doMagic() { obj_->doSomething(); }
private
     MyClass<T>* obj_;
}

Note that in C++ names starting with an underscore are reserved for the implementation, so I have changed _obj for obj_.