我是 python 新手，我试图运行这个花哨的装饰器代码

Question

class Square:
    def _init_(self,side):
        self._side = side
    @property
    def side(self):
        return self._side
    @side.setter
    def side(self,value):
        if value >= 0:
            self._side = value
        else:
            print("error")
    @property
    def area(self):
        return self._side **2
    @classmethod
    def unit_square(cls):
        return cls(1)
s = Square(5)
print(s.side)
print(s.area)

但我收到错误（s = Square(5) TypeError: Square() 没有参数）我无法弄清楚

Answer 1

init 方法应该有双下划线（__）。把方法改成__init__

def __init__(self, side):
    self._side = side

参考：https://dbader.org/blog/python-dunder-methods