python - 如何将内容传递给python中的类实例

Question

我有一个 Book 类，现在基本上只返回内容，但我有一个外部文件需要读取，然后将内容传递给该实例，例如，我开始将书实例声明为 b1

class Book():
    def __init__(self,poem="empty"):
        self.poem = poem

    def __str__(self):
        return self.poem

def reading(instance, file_content):
    list_of_content = []
    with open(file_content, "r") as f:
        for i in f:
            list_of_content.append(i.split())
    flatten = [item for sublist in list_of_content for item in sublist]
    string = " ".join(flatten) 
    instance = Book(string)
    return instance


b1 = Book() # book has a default value so it wont make any error
reading(b1, "file.txt")
print("File contains:",b1) # prints empty, because reading function has not passed any data i think

问题是现在它总是只打印“空”，我怎样才能将我从文件中读取的数据传递给在 reading() 时调用的实例，这是为了学习目的。

Answer 1

reading 应该是类的一个方法，但您也可以在创建时只初始化 Book:

class Book():

    def __init__(self,filename):
        list_of_content = []
        with open(filename) as f:
            for line in f:
                list_of_content.append(line.split())
        flatten = [item for sublist in list_of_content for item in sublist]
        string = " ".join(flatten) 
        self.poem = string

    def __str__(self):
        return self.poem

b1 = Book('file.txt')
print("File contains:",b1)

如果您仍想创建空书并可能将不同的文件读入同一本Book，请将read 设为一个方法:

class Book():
    def __init__(self,poem='<empty>'):
        self.poem = poem

    def read(self,filename):        
        list_of_content = []
        with open(filename) as f:
            for line in f:
                list_of_content.append(line.split())
        flatten = [item for sublist in list_of_content for item in sublist]
        string = " ".join(flatten) 
        self.poem = string

    def __str__(self):
        return self.poem

b1 = Book()
print("File contains:",b1)
b1.read('file.txt')
print("File now contains:",b1)