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Question

我开始使用类来创建简单的联系人输出，然后使用这样的更新版本：

My Contacts
-----------
??? Murphy              555-555-8980
George Smith            555-555-2323
Mike Johnson            555-555-4780
-----------

My Contacts
-----------
Cade Murphy             555-555-8980
President George Smith  555-555-2323
Professor Mike Johnson  555-555-4780
----------

我已正确设置了这些功能，但我不知道要放入class Contact的内容，以便打印出我想要的内容。

class Contact:
    # I don't know what to put here     

def print_directory(contacts):
    print("My Contacts")
    print("-----------")
    for person in contacts:
        print(person)
    print("-----------\n")


def main():
    champ = Contact("???", "Murphy", "555-555-8980")
    president = Contact("George", "Smith", "555-555-2323")
    professor = Contact("Mike", "Johnson", "555-555-4780")

    contacts = [champ, president, professor]

    print_directory(contacts)

    champ.set_first_name("Cade")
    president.set_title("President")
    professor.set_title("Professor")

    print_directory(contacts)


main()

我尝试过关于课程的教程和文档，但是我没有到达任何地方。任何帮助将不胜感激，谢谢。

Answer 1

如果您只想设置属性：

professor.first_name = "Mike"

这会添加一个属性first_name，其值为Mike，动态

如果你需要一个二传手，请多做一次：

class Contact(object):

    def set_first_name(self, fn):
        self._first_name = fn

和

professor.set_first_name(Mike)

你可能想要使用__init__这个类构造函数，它使它更加OO：

class Contact(object):

    def __init__(self, first_name, last_name, tel):
        # convention: private members' name usually start with '_'
        self._first_name = first_name
        self._last_name = last_name
        self._tel = tel

然后你可以使用：

professor = Contact("Mike", "Johnson", "555-555-4780")

如果你想要更多的pythonic OO，你可以使用setter / getter装饰器：

class Contact（object）：

@property
def first_name():
    # this is a getter
    print "getter!"
    return self._first_name

@first_name.setter
def first_name(self, first_name):
    # this is a setter
    print "setter!"
    self._first_name = first_name

你可以：

professor = Contact()
professor.first_name = "Mike"  # this calls the setter, set value of `_first_name`
print(professor.first_name) # this calls the getter, return value of `_first_name`

注意：Python中的一项约定是将私人成员命名为_，例如_first_name。这暗示外部不应直接操作此成员。

希望这有帮助。

小更新：我认为在Python中，代表电话簿的list Contact在大多数情况下都足够了，包括需要使用某些ORM / ODM lib将其写入数据库的情况。不需要PhoneBook课程。只是我的想法。

小更新2：有人在回答和评论中说__str__，这是一个好点。请参阅@Bryan Zeng的回答。还有一个名为__repr__的东西提供与__str__类似的功能。

这个问题可能会有所帮助：Difference between __str__ and __repr__ in Python

我推荐了一本书＆＃34;流利的Python＆＃34;，它引入了很多＆＃34;魔术功能＆＃34; （OO章节中的以双下划线开头和结尾的函数），这将为Python OO编程提供很大的帮助。

小更新3：修复setter / getter装饰器上的错误。我暂时没有使用它，我写错了...... @setter应该是@first_name.setter。对此抱歉。

Answer 2

首先，需要进行初始化，以便放置__init__函数。

class Contact:
    def __init__(self, first_name, last_name, phone_number): # Arguments. self is always needed.
        self.first_name = first_name
        self.last_name = last_name
        self.phone_number = phone_number

那么这个类有三个变量。其次，它需要变成一个字符串。

class Contact:
    def __init__(self, first_name, last_name, phone_number): # Arguments. self is always needed.
        self.first_name = first_name
        self.last_name = last_name
        self.phone_number = phone_number

    def __str__(self):
        return "%s %s \t %s" % (self.first_name, self.last_name, self.phone_number)

您在代码中有一个set_first_name函数，因此请创建一个

class Contact:
    def __init__(self, first_name, last_name, phone_number): # Arguments. self is always needed.
        self.first_name = first_name
        self.last_name = last_name
        self.phone_number = phone_number

    def __str__(self):
        return "%s %s \t %s" % (self.first_name, self.last_name, self.phone_number)

    def set_first_name(self, first_name):
        self.first_name = first_name

最后，您的代码中有一个set_title函数。

class Contact:
    def __init__(self, first_name, last_name, phone_number): # Arguments. self is always needed.
        self.first_name = first_name
        self.last_name = last_name
        self.phone_number = phone_number

    def __str__(self):
        return "%s %s \t %s" % (self.first_name, self.last_name, self.phone_number)

您在代码中有一个set_first_name函数，因此请创建一个

class Contact:
    def __init__(self, first_name, last_name, phone_number): # Arguments. self is always needed.
        self.first_name = first_name
        self.last_name = last_name
        self.phone_number = phone_number
        self.title = None

    def __str__(self):
        if self.title is None:
            return "%s %s \t %s" % (self.first_name, self.last_name, self.phone_number)
        else:
            return "%s %s %s \t %s" % (self.title, self.first_name, self.last_name, self.phone_number)

    def set_first_name(self, first_name):
        self.first_name = first_name

    def set_title(self, title):
        self.title = title

Answer 3

在面向对象编程（OOP）中，类定义了包含相关属性的对象。

在类中表示联系人的最简单方法是（您猜对了）使用Contact类，但为了清洁，我们还会有一个电话簿类：

class Contact:
    def __init__(self, first_name, last_name, phone_number):
        # The init method is the one called when you instantiate the class
        # Ideally it takes all mandatory parameters, that is
        # Information without which the object would not fulfill its job

        # We could do other stuff, but here we only save the parameters given
        # as object properties so you can refer to them later
        self.first_name = first_name
        self.last_name = last_name
        self.phone_number = phone_number

    def print_info(self):
        # Ideally a data operation class wouldn't be printing anything
        # We should return this information as a string and handle it elsewhere
        # We'll print it right out of the bat though to keep it straightforward
        print(self.first_name, self.last_name, self.phone_number)

class Phonebook:
    def __init__(self):
        # The phonebooks don't need any special stuff to exist, 
        # so the only parameter taken is the implicit self
        self.contact_list = []

    def add(self, contact):
        # Here is a method that adds an instance of Contact to the list
        self.contact_list.append(contact)
        return self

    def get_all(self):
        # Again, IDEALLY this would be what we would call
        # And this list would be handled elsewhere to be printed...
        return self.contact_list

    def print_all(self):
        # ...however this is a small program, and this class can print itself
        print("My contacts")
        print("-----------")
        for contact in self.contact_list:
            contact.print_info()
        print("-----------\n")

def main():

    phonebook = Phonebook() # Phonebook had no __init__, so no params are used

    # Then we create the contacts (remember the params we defined at __init__)
    champ = Contact("???", "Murphy", "555-555-8980")
    president = Contact("George", "Smith", "555-555-2323")
    professor = Contact("Mike", "Johnson", "555-555-4780")

    # And we add them to the phonebook (remember method add)
    # We can chain all .add calls because of the "return self" line
    phonebook.add(champ).add(president).add(professor)

    # We can then print everything!
    phonebook.print_all()

main()

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正如已经指出的那样，Python有一个内置的__str__方法，我们不需要定义print_info()。我没有改变我的代码块，因为我猜明明解释方法对于初学者来说会更好。不过，更合适的方法是定义__str__然后print(contact)而不是调用contact.print_info()。

（Python初学者）需要在课程上开始

3 个答案:

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