class Students():
    def __init__(self, id, name, age):
        self.name = name
        self.age = age
        self.id = id

    def __str__(self):
        return f'学号:{self.id},名字：{self.name},年龄：{self.age}'


class StudentsList:
    def __init__(self, capacity=10):
        self.capacity = capacity
        self.size = 0
        self.data = {}

    def add(self, student):
        if len(self.data) >= self.capacity:
            print('已满，无法添加学生')
            return
        if student.id in self.data:
            print(f'{student.id}已添加')
        else:
            self.data[student.id] = student
            self.size += 1
            print(f'{student.name}已添加')

    def delete(self, id):
        if id in self.data:
            del self.data[id]
            self.size -= 1
            print(f'{id}的学生已删除')
        else:
            print('查无此人')

    def update(self, id, name=None, age=None):
        if id in self.data:
            s = self.data[id]
            if name:
                s.name = name
            if age:
                s.age = age
            print(f'{id}学号的学生信息已更新')
        else:
            print('查无此人')

    def list(self):
        if not self.data:
            print("学生列表为空！")
        else:
            print("当前列表：")
            for student in self.data.values():
                print(student)


student_list = StudentsList()
stu1 = Students(21001, '王五', 18)
stu2 = Students(21002, '马六', 20)
student_list.add(stu1)
student_list.add(stu2)
student_list.list()
student_list.delete(21001)
student_list.update(21002, '米老鼠', 22)
student_list.list()