我不熟悉Python OOP并尝试创建OOP程序来管理库。这段代码来自一本书。

此代码正常工作，但我需要了解action()在选择特定选项时如何调用相应函数，例如：当我选择1时，即使我们不调用show_notes函数，也会调用它。

Menu.py

import sys

from notebook import Notebook, Note

class Menu:

'''Display a menu and respond to choices when run.'''

def __init__(self):

self.notebook = Notebook()

self.choices = {

"1": self.show_notes,

"2": self.search_notes,

"3": self.add_note,

"4": self.modify_note,

"5": self.quit

}

def display_menu(self):

print("""

Notebook Menu

1. Show all Notes

2. Search Notes

3. Add Note

4. Modify Note

5. Quit

""")

def run(self):

'''Display the menu and respond to choices.'''

while True:

self.display_menu()

choice = input("Enter an option: ")

action = self.choices.get(choice)

if action:

action()

else:

print("{0} is not a valid choice".format(choice))

def show_notes(self, notes=None):

if not notes:

notes = self.notebook.notes

for note in notes:

print("{0}: {1}\n{2}".format(

note.id, note.tags, note.memo))

def search_notes(self):

filter = input("Search for: ")

notes = self.notebook.search(filter)

self.show_notes(notes)

def add_note(self):

memo = input("Enter a memo: ")

self.notebook.new_note(memo)

print("Your note has been added.")

def modify_note(self):

id = input("Enter a note id: ")

memo = input("Enter a memo: ")

tags = input("Enter tags: ")

if memo:

self.notebook.modify_memo(id, memo)

if tags:

self.notebook.modify_tags(id, tags)

def quit(self):

print("Thank you for using your notebook today.")

sys.exit(0)

if __name__ == "__main__":

Menu().run()notebook.py

import datetime

# Store the next available id for all new notes

last_id = 0

class Note:

'''Represent a note in the notebook. Match against a

string in searches and store tags for each note.'''

def __init__(self, memo, tags=''):

'''initialize a note with memo and optional

space-separated tags. Automatically set the note's

creation date and a unique id'''

self.memo = memo

self.tags = tags

self.creation_date = datetime.date.today()

global last_id

last_id += 1

self.id = last_id

def match(self, filter):

'''Determine if this note matches the filter

text. Return True if it matches, False otherwise.

Search is case sensitive and matches both text and

tags.'''

return filter in self.memo or filter in self.tags

class Notebook:

'''Represent a collection of notes that can be tagged,

modified, and searched.'''

def __init__(self):

'''Initialize a notebook with an empty list.'''

self.notes = []

def new_note(self, memo, tags=''):

'''Create a new note and add it to the list.'''

self.notes.append(Note(memo, tags))

def _find_note(self, note_id):

'''Locate the note with the given id.'''

for note in self.notes:

if str(note.id) == str(note_id):

return note

return None

def modify_memo(self, note_id, memo):

'''Find the note with the given id and change its

memo to the given value.'''

note = self._find_note(note_id)

if note:

note.memo = memo

return True

return False

def modify_tags(self, note_id, tags):

'''Find the note with the given id and change its

tags to the given value.'''

note = self._find_note(note_id)

if note:

note.tags = tags

return True

return False

def search(self, filter):

'''Find all notes that match the given filter

string.'''

return [note for note in self.notes if

note.match(filter)]