问题类

Question

我试图创建一个名为Record的类,但是当我尝试使用它时,出现问题.我肯定会忽略一些简单的事情.有人介意看看吗？

      class Record:
          def __init__(self, model):
              self.model= model
              self.doc_date = []
              self.doc_pn = []
              print("Record %s has been added.\n") % self             
          def add_doc_date(self, declaration_date):
              self.doc_date.append(declaration_date)
          def add_doc_pn(self, declaration_pn):
              self.doc_pn.append(declaration_pn)
          def __str__(self):
              res = "Name: " + self.model + "\n"
              res = res + "Standard Part Numbers:" + str(self.std_pn) + "\n"
              res = res + "Declaration Part Numbers" + str(self.doc_pn) + "\n"
              return res

Answer 1

res = res + "Standard Part Numbers:" + str(self.std_pn) + "\n"

我看不到self.std_pn任何地方.