Python 对非序列的迭代

Question

我有这段代码可以创建一个笔记并添加到笔记本中。当我运行它时，我得到一个 Iteration over non-sequence 错误。

import datetime
class Note:
    def __init__(self, memo, tags):
        self.memo = memo
        self.tags = tags
        self.creation_date = datetime.date.today()

def __str__(self):
    return 'Memo={0}, Tag={1}'.format(self.memo, self.tags)


class NoteBook:
     def __init__(self):
        self.notes = []

     def add_note(self,memo,tags):
        self.notes.append(Note(memo,tags))

if __name__ == "__main__":
    firstnote = Note('This is my first memo','example')
    print(firstnote)
    Notes = NoteBook()
    Notes.add_note('Added thru notes','example-1')
    Notes.add_note('Added thru notes','example-2')
    for note in Notes:
        print(note.memo)

错误:

C:\Python27\Basics\OOP\formytesting>python notebook.py  Memo=This is my first memo, Tag=example  Traceback (most recent call last):    File "notebook.py", line 27, in       for note in Notes:  TypeError: iteration over non-sequence

Answer 1

您正在尝试迭代返回错误的对象本身。您想要遍历对象内部的列表，在本例中为 Notes.notes(这有点令人困惑的命名，您可能希望通过为笔记本对象的实例使用另一个名称来区分内部列表).

for note in Notes.notes:
    print(note.memo)