python @property 装饰器

class C:
    def __init__(self):
        self._x = None

    @property
    def x(self):
        """I'm the 'x' property."""
        return self._x

    #设置fset，注意x要与@property修饰的方法名称相同
    @x.setter
    #这个fset名称没有限制，建议与x相同
    def x(self, value):
        self._x = value

    #设置fdel
    @x.deleter
    def x(self):
        del self._x

""" @property, @*.setter"""
from datetime import datetime

class Man:
    def __init__(self, birthYear=None, gender=None, weight=None):
        """1.使用@property可以隐藏私有属性，例如把'_birthYear'属性隐藏，
             把property对象birthYear作为对外的属性"""

        self._birthYear = birthYear
        self._gender = gender
        self._weight = weight

    @property
    def birthYear(self):
        return self._birthYear
    
    @birthYear.setter
    def birthYear(self, value):
       """2.可以在setter中对属性输入进行限制或者其他操作"""
        assert not value > datetime.now().year, f'please input the right value!'
        self._birthYear = value

    @property
    """3.获取年龄直接用obj.age，而不需写成方法obj.age(), 更加自然方便"""
    def age(self):
        return datetime.now().year - self._birthYear

    @property
    def gender(self):
        return self._gender

    @property
    def weight(self):
        return self._weight
    
    @weight.setter
    def weight(self, value):
        self._weight = value

    @weight.deleter
    def weight(self):
        del self._weight

lilei = Man(1996, 'male', 180)
age = lilei.age
print('Lilei今年{}岁\n'.format(age))

# 设置性别
try:
    lilei.gender = 'female'
except:
    print('性别无法进行更改！\n')

# 更新体重
print(f'lilei减肥前的体重：{lilei.weight}\n')
lilei.weight = 200
print(f'lilei减肥后的体重：{lilei.weight}\n')
print('lilei减肥失败后一气之下将体重信息删了\n')
del lilei.weight
try:
    print('lilei的体重{}'.format(lilei.weight))
except:
    print('找不到lilei的体重信息！')

# 初始版本
class Celsius:
    def __init__(self, temperature = 0):
        self.temperature = temperature

    def to_fahrenheit(self):
        return (self.temperature * 1.8) + 32

# 实例化
human = Celsius()
# 设置温度
human.temperature = 37
# 获取温度值
print(human.temperature)
# 调用内置方法将摄氏度转化为华氏温度
print(human.to_fahrenheit())

# 更新温度限制的版本
class Celsius:
    def __init__(self, temperature=0):
        self.set_temperature(temperature)

    def to_fahrenheit(self):
        return (self.get_temperature() * 1.8) + 32

    # getter method
    def get_temperature(self):
        return self._temperature

    # setter method
    def set_temperature(self, value):
        if value < -273.15:
            raise ValueError("摄氏温度不可能低于 -273.15 ！")
        self._temperature = value

# 实例化
human = Celsius(37)

# 使用添加的getter获取温度值
print(human.get_temperature())

# 调用内置方法将摄氏度转化为华氏温度
print(human.to_fahrenheit())

# 使用添加的setter对温度值进行设置
human.set_temperature(-300)

# Get the to_fahreheit method
print(human.to_fahrenheit())

# 使用 @property 装饰器版本
class Celsius:
    def __init__(self, temperature=0):
        #这里的self.temperture是下面定义的property对线 temperatue
        #所以你会发现在初始化Celsius时， 调用了temperature.setting方法
        self.temperature = temperature

    def to_fahrenheit(self):
        return (self.temperature * 1.8) + 32

    @property
    def temperature(self):
        print("获取温度值...")
        return self._temperature

    @temperature.setter
    def temperature(self, value):
        print("设置温度值...")
        if value < -273.15:
           raise ValueError("摄氏温度不可能低于 -273.15 ！")
        self._temperature = value


# 用property的实现后获取和设置温度值与最初的版本一样！
human = Celsius()
# 设置温度
human.temperature = 37
# 获取温度值
print(human.temperature)
# 调用内置方法将摄氏度转化为华氏温度
print(human.to_fahrenheit())

#测试温度限制功能
human.temperature = -300