引用类型的初始化无效

发生了什么事？以下是它引用的函数。我正试图让它作为一个复制构造函数工作

template <class T>
const queue<Base>& queue<T>::operator=(const queue<Base> &q){
// Doesn't need to copy if they are the same object
if (this != &q){
    delete [] data;
    length = q.length;
    capacity = q.capacity;
    front = q.front;
    data = new T[capacity];
    for (int i = 0; i < capacity; i++){
        data[i] = q.data[i];
    }
}
return this;
}