template wrapper catch function call

I am using this little example code from https://github.com/bblanchon/dllhelper

i want to know how would i catch the function call before it is called? So i could call my own function 1st to set up some stuff.

I need a operator inside DllHelper, im not sure how to do it.

thanks

class ProcPtr {
public:
  explicit ProcPtr(FARPROC ptr) : _ptr(ptr) {}

  template <typename T, typename = std::enable_if_t<std::is_function_v<T>>>
  operator T *() const {
    return reinterpret_cast<T *>(_ptr);
  }

private:
  FARPROC _ptr;
};

class DllHelper {
public:
  explicit DllHelper(LPCTSTR filename) : _module(LoadLibrary(filename)) {}

  ~DllHelper() { FreeLibrary(_module); }

  ProcPtr operator[](LPCSTR proc_name) const {
    return ProcPtr(GetProcAddress(_module, proc_name));
  }

  static HMODULE _parent_module;

private:
  HMODULE _module;
};