如果不在__init__中，如何添加方法属性

Question

如何从外部函数向不是__init__的方法添加属性。

例如

class Year:
    def __init__(self):
        self._list = []
    def add_year(self,year):
        self._year = year
        self._list.append(self._year)
def main():
    year = 1998
    #how do I get this year into the year class to add to list?

Answer 1

如上面的评论所述：

创建实例：

yobj = Year()

并传递要分配的值

year = 1998
yobj.add_year(year)

Answer 2

方法__init__除了在实例化对象时执行外没有什么特别的。这意味着，您可以在代码中的几乎任何地方（不仅在Year中，为__init__的实例分配或获取属性。

class Year:
    def __init__(self):
        # You can define an attribute in __init__
        self.year_list = []

    def add_year(self, year):
        # You can define and access an attribute in any method
        self.last_year_added = year
        self.year_list.append(year)

def main():
    year = 1998

    # You must instantiate a Year first
    my_year = Year()

    # Then execute the method add_year
    my_year.add_year(year)
    my_year.add_year(year + 1)

    print(my_year.year_list)  # [1998, 1999]
    print(my_year.last_year_added) # 1999


    # Note that you can even add attribute outside methods
    my_year.month = 'December'

    print(my_year.month) # December

main()

Answer 3

下面是一个例子，看看是否有帮助

class Dog:

    # Class Attribute
    species = 'mammal'

    # Initializer / Instance Attributes
    def __init__(self, name, age):
        self.name = name
        self.age = age

    # instance method
    def description(self):
        return "{} is {} years old".format(self.name, self.age)

    # instance method
    def speak(self, sound):
        return "{} says {}".format(self.name, sound)

# Instantiate the Dog object
mikey = Dog("Mikey", 6)

# call our instance methods
print(mikey.description())
print(mikey.speak("Gruff Gruff"))

输出如下。

Mikey is 6 years old
Mikey says Gruff Gruff

如果您想了解有关使用python进行面向对象的方式编程的更多信息，请遵循以下教程-[https://realpython.com/python3-object-oriented-programming/][1]