Question

我正在尝试建立一个简单的学生数据库（姓名和年龄）。当我试图删除一个兴奋的学生并打印数据库时，它打印我 import pickle class data_base: data={} class __metaclass__(type): def __iter__(self): for attr in dir(data_base): if not attr.startswith("__"): yield attr def __init__(self): self.write("") def write(self,my_data): pickle.dump( my_data, open( "database.p", "wb" ) ) def read(self): return pickle.load( open( "database.p", "rb" ) ) def delete_student(self): #delete key and value to_delete=raw_input("who do you want to delete? ") my_data=self.read() if to_delete in my_data.__iter__(): my_data.pop(to_delete) self.write(data_base) else: print "no such student" def clear_data_base(self): #delete data baase self.write("") def main(): first_data={"ben":10,"dan":6} my_data_base=data_base() my_data_base.clear_data_base() my_data_base.write(first_data) print my_data_base.read() my_data_base.delete_student() print my_data_base.read()，但如果我试图删除一个不存在的学生，它会打印出数据库。

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Answer 1

问题在于：

self.write(data_base)

您已经将类对象腌制而不是您读入的实例my_data。将您的方法更改为

def delete_student(self):
    #delete key and value
    to_delete=raw_input("who do you want to delete? ")
    my_data=self.read()
    if to_delete in my_data.__iter__():
        my_data.pop(to_delete)
        self.write(my_data)
    else:
        print "no such student"

类对象打印内容的instaed

1 个答案: