How to initialize a class that manages a buffer whose data type is passed at instantiation.

Question

I need to create a Buffer class whose type of variables that constitute the managed buffer is decided at istantiation time. Thus, I need a buffer class of long int bytes, 30 elements long, I will instantiate something like:

GeneralBuffer myLongBuffer(long int, 30); or GeneralBuffer myLongBuffer(LONG, 30);

While if I need a unsigend floating type:

GeneralBuffer myFloatingBuffer(unsigend float, 30); or or GeneralBuffer myLongBuffer(UFLOATING, 30);

Any suggestions?

Answer 1

Since types are a compile-time construct, you can't pass them as arguments to a function. Instead you want templates. Templates allow to instantiate different implementations of a class or function depending on the template type parameters you pass to it. So if you have:

template <typename T>
class GeneralBuffer
{
  private:
    T* internal_buffer;
  public:
    GeneralBuffer(size_t size);
};

You can instantiate GeneralBuffer for int and create an object of that type like so:

GeneralBuffer<int> my_int_buffer(30);

However, this just looks like a reimplementation of std::vector.

Alternatively, if the size of the buffer is also a compile-time constant, you could also pass it as a template parameter:

template <typename T, std::size_t N>
class GeneralBuffer
{
  private:
    T internal_array[N];
  public:
    GeneralBuffer();
};

Which you would use like so:

GeneralBuffer<int, 30> my_int_buffer;

However, this just looks like a reimplementation of std::array.