需要一些帮助将程序更改为面向对象的程序

Question

我一直在创建一个程序作为作业的一部分，并且已经到了有人要求我将书面结构更改为面向对象程序的地步。这意味着创建一个带有方法的类。

这是问题/任务本身：

Question/Task

以下是程序代码，没有改动：

def make_album(id_num, name, band, price):
    """creates and returns a dictionary with keys id_num, name, band, and 
    price, with values populated directly from the function parameters."""
    album_dict = {}
    values = [int(id_num), name, band, float(price), 0, None, None]
    keys = ['id_num', 'name', 'band', 'price', 'total_sales', 
              'first_date_recorded', 'last_date_recorded']
    for i in range(len(keys)):
        album_dict[keys[i]] = values[i]
    return album_dict

def add_sales(album, date, daily_sales):
    """updates the given album dictionary by incrementing the total_sales 
    value by the given number of sales for that day"""
    if album['first_date_recorded'] == None:
        album['first_date_recorded'] = date
        album['last_date_recorded'] = date
    elif date > album['last_date_recorded']:
        album['last_date_recorded'] = date
    elif date < album['first_date_recorded']:
        album['first_date_recorded'] = date
    album['total_sales'] += daily_sales

def print_album(album):
    """Prints the given album in a format like the following, where the 
    first and last lines are both made of 40 hyphen ('-') characters"""
    print('-' * 40)
    print('Album Name: {}'.format(album['name']))
    print('Band: {}'.format(album['band']))
    print('Purchase Price: ${:.2f}'.format(album['price']))
    print('First Recorded Sale: {}'.format(album['first_date_recorded']))
    print('Last Recorded Sale: {}'.format(album['last_date_recorded']))
    print('Total Sold: {}'.format(album['total_sales']))
    print('-' * 40)

def extract_album(lines, index):
    """takes a list of lines and an index into that list and returns a 
    album dictionary"""
    id_num, name, band, price = lines[(index + 1):(index + 5)]
    album_dict = make_album(id_num, name, band, price)
    return album_dict

def extract_all_albums(lines):
    """returns a list of albums in the same order as they are encountered 
    input lines list"""
    album_dict_list = []
    for i, line in enumerate(lines):
        if line == '<album>':
            album = extract_album(lines, i)
            album_dict_list.append(album)
    return album_dict_list

def read_sales(lines, albums):
    """locates the sales section if there is one and for each sales record 
    it should call the add_sales function on the appropriate album to update 
    the number of albums sold"""
    start_tag = 0
    end_tag = 0
    for i, line in enumerate(lines):
        if line == '<sales>':
            start_tag = i
        elif line == '</sales>':
            end_tag = i
    for line in lines[(start_tag + 1):(end_tag)]:
        date, id_num, sales = line.split(',')
        for album in albums:
            if album['id_num'] == int(id_num):
                add_sales(album, date, int(sales))

这是我的第一次尝试（不工作）：

class Album:
    """defines the class Album.
    Data attributes: id_num of album,
                     name of album,
                     band who wrote album,
                     price of the album.
    """


    def __init__(self, id_num, name, band, price):
        """creates and new album object, a dictionary with keys id_num, 
        name, band, and price"""
        self.id_num = id_num
        self.name = name
        self.band = band
        self.price = price
        self.album_dict = {}
        values = [int(self.id_num), self.name, self.band, float(self.price), 
                  0, None, None]
        keys = ['id_num', 'name', 'band', 'price', 'total_sales', 
                'first_date_recorded', 'last_date_recorded']
        for i in range(len(keys)):
            self.album_dict[keys[i]] = values[i]

    def add_sales(self,):
        """updates the given album dictionary by incrementing the 
        total_sales value by the given number of sales for that day"""
        if self.album_dict['first_date_recorded'] == None:
            self.album_dict['first_date_recorded'] = self.date
            self.album_dict['last_date_recorded'] = self.date
        elif self.date > self.album_dict['last_date_recorded']:
            self.album_dict['last_date_recorded'] = self.date
        elif self.date < self.album_dict['first_date_recorded']:
            self.album_dict['first_date_recorded'] = self.date
            self.album_dict['total_sales'] += self.daily_sales

    def __str__(self):
        """Prints the given album in a format where the first and last lines 
        are both made of 40 hyphen ('-') characters"""
        print('-' * 40)
        print('Album Name: {}'.format(self.album['name']))
        print('Band: {}'.format(self.album['band']))
        print('Purchase Price: ${:.2f}'.format(self.album['price']))
        print('First Recorded Sale: 
             {}'.format(self.album['first_date_recorded']))
        print('Last Recorded Sale: 
             {}'.format(self.album['last_date_recorded']))
        print('Total Sold: {}'.format(self.album['total_sales']))
        print('-' * 40)

def extract_album(lines, index):
    """takes a list of lines and an index into that list and returns a 
    album dictionary"""
    id_num, name, band, price = lines[(index + 1):(index + 5)]
    album_dict = make_album(id_num, name, band, price)
    return album_dict

def extract_all_albums(lines):
    """returns a list of albums in the same order as they are encountered 
    input lines list"""
    album_dict_list = []
    for i, line in enumerate(lines):
        if line == '<album>':
            album = extract_album(lines, i)
            album_dict_list.append(album)
    return album_dict_list

def read_sales(lines, albums):
    """locates the sales section if there is one and for each sales record 
    it should call the add_sales function on the appropriate album to update 
    the number of albums sold"""
    start_tag = 0
    end_tag = 0
    for i, line in enumerate(lines):
        if line == '<sales>':
            start_tag = i
        elif line == '</sales>':
            end_tag = i
    for line in lines[(start_tag + 1):(end_tag)]:
        date, id_num, sales = line.split(',')
        for album in albums:
            if album['id_num'] == int(id_num):
                add_sales(album, date, int(sales))

在我的尝试中有几件事我知道是错误的，但我似乎无法理解 OOP，因此很难在没有指导的情况下构造类和方法。我还没有完成任何对现在是类和方法的函数的调用，但我知道该程序将无法工作。感谢您的帮助，谢谢！

Answer 1

为了使类工作，输入参数self 需要在类中的每个方法（函数）中。因此，您需要修改 extract_album、extract_all_albums 和 read_sales 函数以将 self 作为第一个函数输入。例如，extract_album 必须重写为：

def extract_album(self, lines, index):
    """takes a list of lines and an index into that list and returns a 
    album dictionary"""
    self.id_num, self.name, self.band, self.price = lines[(index + 1):(index + 5)]
    album_dict = make_album(self.id_num, self.name, self.band, self.price)
    return album_dict