不，老师名单

Question

在收到关于我的前一个问题的反馈后，我决定再试一个项目，看看我是否理解O.O.P.。这个想法也是基于我这个学期正在做的项目--我的课堂上的互动学校巡回演出。

这个程序让你做了一堆老师的例子，然后把它们全部打印出来。

class Teacher:
    def __init__(self, name, subject, room_number):
        self.name = name
        self.subject = subject
        self.room_number = room_number
    def print_info(self):
        return self.name, self.subject, self.room_number


def instagator(teachers: list) -> list:
    """Creates a version of the teacher class"""
    print("")
    name = input("Please enter a teachers name: ")
    subject = input("Please enter that teachers subject: ")
    room_number = input("Please enter what room that teacher teaches in: ")
    # Makes the varible that holds the instance names after the teacher
    globals()[name] = Teacher(name, subject, room_number)
    teachers.append(globals()[name])
    return teachers


teachers = []
print("Please enter the name of 10 teachers, the subject they teach, and the room they teach that subject in.")
for _ in range(10):
    teachers = instagator(teachers)
print("\n")
for teacher in teachers:
    info = teacher.print_info()
    print(f"{info[0].capitalize()} teaches {info[1]} in room {info[2]}. \n")

和以前一样，我只想知道我的O.P.方法是否有什么问题，因为我对自己正在做的事情仍然知之甚少。

Answer 1

1. 您的Teacher类的用户应该能够在设置name、subject和room_number属性之后修改它们吗？如果不是，则将_放在这些名称的开头，将其设置为私有。
2. Python有一个神奇的方法__repr__，它将它们转换为用于打印的字符串。这将是一个很好的地方放置您的格式逻辑。
3. 我不知道globals会做些什么，但一般情况下，您不应该碰globals。
4. 您的instagator函数说它创建了一个Teacher，但是它也接受了一个现有教师的列表，并将其附加到其中，然后返回它。试着让你的函数做一件显而易见的事情，而不是做多个不明显的事情。

如果您的instagator函数只执行它说的一件事情(创建一个Teacher)，并且如果您将字符串格式移动到__repr__函数中，而不是有一个中间print_info实际上不打印任何东西，那么代码就变得简单了一些：

class Teacher:
    def __init__(self, name: str, subject: str, room_number: str):
        self._name = name
        self._subject = subject
        self._room_number = room_number

    def __repr__(self) -> str:
        return f"{self._name.capitalize()} teaches {self._subject} in room {self._room_number}."


def instagator() -> Teacher:
    """Creates a Teacher from user input."""
    print("")
    name = input("Please enter a teachers name: ")
    subject = input("Please enter that teachers subject: ")
    room_number = input("Please enter what room that teacher teaches in: ")
    return Teacher(name, subject, room_number)


print("Please enter the name of 10 teachers, the subject they teach, and the room they teach that subject in.")
teachers = [instagator() for _ in range(10)]
print("\n")

for teacher in teachers:
    print(teacher)

注意，由于instagator返回一个Teacher，所以我可以使用一个简单的列表理解来构建所有Teachers的列表，其中一个对应于range中的每个数字。由于我实现了__repr__，所以我不需要多行代码来构建要打印的字符串；我可以直接打印teacher，这将自动转换为我想要的格式化字符串。

我不认为为用户输入提供构造函数提示符通常不是很好的实践，但对于这样的实践练习，我认为演示如何使用类封装与构建对象相关的所有逻辑是可以的：

class Teacher:
    def __init__(self):
        """Creates a Teacher from user input."""
        print("")
        self._name = input("Please enter a teachers name: ")
        self._subject = input("Please enter that teachers subject: ")
        self._room_number = input("Please enter what room that teacher teaches in: ")

    def __repr__(self) -> str:
        return f"{self._name.capitalize()} teaches {self._subject} in room {self._room_number}."


print("Please enter the name of 10 teachers, the subject they teach, and the room they teach that subject in.")
teachers = [Teacher() for _ in range(10)]
print("\n")

for teacher in teachers:
    print(teacher)