面向对象案例-烤红薯

类名设计：SweetPotato

分析“烤红薯”的属性

烤的时长：roast_time

烤的状态：roast_state

烤的风味：condiments

分析“烤红薯”的方法

烤红薯: roast

添加调料:add_condiments

烤的时长对应红薯的状态：

定义红薯类：

# 自定义红薯类
class SweetPotato(object):

    def __init__(self):
        # 烤的时长
        self.roast_time = 0
        # 烤的状态
        self.roast_state = "生的"
        # 调味品
        self.condiments = []

    # 烤红薯
    def roast(self, time):
        # 计算总的时间
        self.roast_time += time
        # 焦了
        if self.roast_time > 8:
            self.roast_state = "焦了"
        elif self.roast_time > 5:
            self.roast_state = "熟了"
        elif self.roast_time > 3:
            self.roast_state = "半生不熟"
        else:
            self.roast_state = "生的"

    # 添加调料
    def add_condiment(self, name):
        self.condiments.append(name)

    # 追踪属性变化
    def __str__(self):
        name = ",".join(self.condiments) if self.condiments else "原味"
        return """烤成的"%s"[%s]的红薯""" % (self.roast_state, name)

定义异常类：

# 自定义异常类
class TimeError(Exception):

    def __init__(self, time):
        self.time = time

    def __str__(self):
        return "亲!您传入的time实参数值有误!{time=%d}" % self.time

最终的红薯类：

# 自定义红薯类
class SweetPotato(object):

    def __init__(self):
        # 烤的时长
        self.roast_time = 0
        # 烤的状态
        self.roast_state = "生的"
        # 调味品
        self.condiments = []

    # 烤红薯
    def roast(self, time):
        if time <= 0:
            raise TimeError(time)
        # 计算总的时间
        self.roast_time += time
        # 焦了
        if self.roast_time > 8:
            self.roast_state = "焦了"
        elif self.roast_time > 5:
            self.roast_state = "熟了"
        elif self.roast_time > 3:
            self.roast_state = "半生不熟"
        else:
            self.roast_state = "生的"

    # 添加调味品
    def add_condiment(self, name):
        self.condiments.append(name)

    # 追踪属性变化
    def __str__(self):
        name = ",".join(self.condiments) if self.condiments else "原味"
        return """烤成的"%s"[%s]的红薯""" % (self.roast_state, name)


if __name__ == '__main__':
    sp = SweetPotato()
    sp.roast(4)
    sp.roast(3)
    sp.add_condiment("孜然")
    sp.add_condiment("芥末")
    print(sp)

例子：

# 自定义红薯类
class SweetPotato(object):

    def __init__(self):
        # 烤的时长：roast_time
        self.roast_time = 0
        # 烤的状态：roast_state
        self.roast_state = "生的"
        # 烤的风味：condiments
        self.__condiments = []

    # 烤红薯
    def roast(self, time):
        # 烤的总时长
        self.roast_time += time
        # 通过总时长判断红薯的状态
        # [0,)
        if self.roast_time < 3:
            pass
        # [3,5)
        elif self.roast_time < 5:
            self.roast_state = "半生不熟"
        # [5,8)
        elif self.roast_time < 8:
            self.roast_state = "熟了"
        # [8,+)
        else:
            self.roast_state = "焦了"

    # 添加佐料
    def add_condiments(self, name):
        self.__condiments.append(name)

    # 追踪属性值变化
    def __str__(self):
        # # 定义一个局部变量 保存口味
        # name = None
        # # 判断是否是原味
        # if not self.condiments:
        #     name = "原味"
        # else:
        #     name = ",".join(self.condiments)
        # 改成三目运算符
        name = "原味" if not self.__condiments else ",".join(self.__condiments)
        return "红薯状态:%s,口味: %s" % (self.roast_state, name)


# 创建一个红薯对象
sp = SweetPotato()
# 烤1分钟
sp.roast(1)
# sp.add_condiments("孜然")
# sp.add_condiments("香辣")
# 再烤4分钟
sp.roast(4)
sp.add_condiments("孜然")
sp.roast(3)
print(sp)