python class

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以__开头的是私有属性

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class Document():

WELCOME_STR = 'Welcome! The context for this book is {}.'

def __init__(self, title, author, context):
    print('init function called')
    self.title = title
    self.author = author
    self.__context = context

# 类函数
@classmethod
def create_empty_book(cls, title, author):
    return cls(title=title, author=author, context='nothing')

# 成员函数
def get_context_length(self):
    return len(self.__context)

# 静态函数
@staticmethod
def get_welcome(context):
    return Document.WELCOME_STR.format(context)

empty_book = Document.create_empty_book('What Every Man Thinks About Apart from Sex', 'Professor Sheridan Simove')

print(empty_book.get_context_length()) print(empty_book.get_welcome('indeed nothing'))

########## 输出 ##########

init function called 7 Welcome! The context for this book is indeed nothing.