03python面向对象编程3

案例学习

# 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

对以上模块进行测试：

In [1]: from notebook import Note

In [2]: n1 = Note("hello first")

In [3]: n2 = Note("hello again")

In [4]: n1.id
Out[4]: 1

In [5]: n2.id
Out[5]: 2

In [6]: n1.match('hello')
Out[6]: True

In [7]: n2.match('second')
Out[7]: False

 接下来创建我们的笔记本：

# notebook.py
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)]

检测：

In [1]: from notebook import  Note,Notebook

In [2]: n = Notebook()

In [3]: n.new_note('hello world')

In [4]: n.new_note('hello again')

In [5]: n.notes
Out[5]: [<notebook.Note at 0x4be87f0>, <notebook.Note at 0x4bc3358>]

In [6]: n.notes[0].id
Out[6]: 1

In [7]: n.notes[1].id
Out[7]: 2

In [8]: n.notes[0].memo
Out[8]: 'hello world'

In [9]: n.notes[1].memo
Out[9]: 'hello again'

In [10]: n.search('hello')
Out[10]: [<notebook.Note at 0x4be87f0>, <notebook.Note at 0x4bc3358>]

In [11]: n.search('world')
Out[11]: [<notebook.Note at 0x4be87f0>]

In [12]: n.modify_memo(1,'hi world')
Out[12]: True

接下来是实现菜单接口，接口只需要简单的提供一个菜单，并允许用户输入他们的选择：

import sys
from notebook import Notebook

class Menu:
    """Display a menu and respond to choices when run."""

    def __init__(self):
        self.notebook = Notebook()
        self.choices = {
            "": self.show_notes,
            "": self.search_notes,
            "": self.add_note,
            "": self.modify_note,
            "": 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 Menu

1. Show all Notes
2. Search Notes
3. Add Note
4. Modify Note
5. Quit

Enter an option: 1

Notebook Menu

1. Show all Notes
2. Search Notes
3. Add Note
4. Modify Note
5. Quit

Enter an option: 3
Enter a memo: 'nihao'
Your note has been added.

Notebook Menu

1. Show all Notes
2. Search Notes
3. Add Note
4. Modify Note
5. Quit

Enter an option: 1
1:
'nihao'

Notebook Menu

1. Show all Notes
2. Search Notes
3. Add Note
4. Modify Note
5. Quit

Enter an option: 4
Enter a note id: 1
Enter a memo: 'wohao'
Enter tags: 'ok'

Notebook Menu

1. Show all Notes
2. Search Notes
3. Add Note
4. Modify Note
5. Quit

Enter an option: 1
1: 'ok'
'wohao'

Notebook Menu

1. Show all Notes
2. Search Notes
3. Add Note
4. Modify Note
5. Quit

Enter an option: 5
Thank you for using your notebook today.