Type Definition xgboost_sys::XGBCallbackDataIterNext

pub type XGBCallbackDataIterNext = Option<unsafe extern "C" fn(data_handle: DataIterHandle, set_function: XGBCallbackSetData, set_function_handle: DataHolderHandle) -> c_int>;

\brief The data reading callback function. The iterator will be able to give subset of batch in the data.

If there is data, the function will call set_function to set the data.

\param data_handle The handle to the callback. \param set_function The batch returned by the iterator \param set_function_handle The handle to be passed to set function. \return 0 if we are reaching the end and batch is not returned.