CODEWITHSUNDEEP
c++
moonkey69420
moonkey69420

Reputation: 113

Error: No Matching Constructor when trying to construct a templated object from a vector value

I have the following templated classes MyObject and SmallObject. Below, I have a constructor for a MyObject that takes a vector as input and converts each item in the vector into a SmallObject. However, when it runs in tests, it returns an error for no matching constructor.

I can't tell what is wrong, my guess was that somehow the values I'm pulling from the vector are not of type T, but I don't understand how this could be the case. This is also a simplified snippet of the relevant parts so don't worry about the fact it's not doing anything with the SmallObj and leaking memory

template<typename T>
SmallObj<T>::SmallObj(T& value) : _value(value) {}

template<typename T>
MyObject<T>::MyObject(const std::vector<T>& values) {
  int n = values.size();

  for (int i = 0; i < n; i++) {
    SmallObject<T>* node = new SmallObject<T>(values[i]); // error: no matching constructor
  }
}

Upvotes: 1

Views: 38

Answers (1)

songyuanyao
songyuanyao

Reputation: 172964

The parameter values is passed as reference to const, then values[i] returns const T&. While the constructor of SmallObj takes reference to non-const which can't bind to constant. If it's not supposed to modify the argument you can change the constructor to take reference to const.

template<typename T>
SmallObj<T>::SmallObj(const T& value) : _value(value) {}

Upvotes: 1

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