main.dart

class Order{
  var _id;
  var _reference;
  var _date;
  Order(_id, _reference, _date){
    this._id = _id;
    this._reference = _reference;
    this._date = _date;
  }
  
  getInfo(){
    return 'Your order information:' + '\n---------------------------------\n'+'\n ID: $_id'+ '\n---------------------------------\n'+' Reference: $_reference'+  '\n---------------------------------\n' + ' Date: $_date'  +  '\n---------------------------------\n';
  }
}

void main(){
  var order1 = new Order(1, 'ref1', new DateTime.now());
  print(order1.getInfo());
}