python __init__

  现在感觉才搞明白一些有关类、实例对象、self等关于类的一些知识,顺带写出来吧。

本人这块小白,也没有过面向对象编程的经验,这块确实理解有些吃力。看了知乎上的帖子后,才发现,似乎很简单。(贴子在这,想看原文的小伙伴可以直接跳转:https://www.zhihu.com/question/46973549

1.类(个人理解就是比如:“学生”这个名词,就是把学生1、学生2....归为一类):

class Students:
    pass

print(Students)
#结果:
<class '__main__.Students'>

这就创建了一个关于学生的类。结果是一个类

2.对象(个人理解就比如:学生张三、学生李4......,是一个真正的实体):

stu1 = Students()
print(stu1)

#结果
#<__main__.Students object at 0x03CBAF50>

实例化的学生就出来了。结果是一个学生对象。

3.但是这个“stu1”没“血肉”啊!

stu1.name = "张三"
stu1.gender = ""
print(stu1.name,stu1.gender)

这样是有“血肉”了,但是这样很麻烦!每次都得写stu1啊,我还想早点打王者呢?也没起到封装的效果。

 

class Students:
    def __init__(self,name,gender,scores):
        self.name = name
        self.gender = gender
        self.scores = scores

stu1 = Students("张三","",[59,60,99])
print(stu1)
print(stu1.name,stu1.gender,stu1.scores)
#结果:
<__main__.Students object at 0x032D71D0>
张三 男 [59, 60, 99]

这不就好起来了么!(大仙粉,哈哈)

 

4.self:

结论:self就是上面的stu1(实例化的对象本身)

那上面的输出就解释清楚了啊!是不是!

那我这样呢?

# coding:utf-8
class Book(object):
 
    def __init__(self, title):
        self.title = title
 
    @classmethod
    def class_method_create(cls, title):
        book = cls(title=title)
        return book
 
    @staticmethod
    def static_method_create(title):
        book= Book(title)
        return book

book1 = Book.__init__(book1,"use instance_method_create book instance")  #我就传他本身,试试
print(book1)
book2 = Book.class_method_create("use class_method_create book instance")
book3 = Book.static_method_create("use static_method_create book instance")
print(book1.title)
print(book2.title)
print(book3.title)
Traceback (most recent call last):
  File "C:\Users\Administrator\Desktop\FunandWay.py", line 17, in <module>
    book1 = Book.__init__(book1,"use instance_method_create book instance")
NameError: name 'book1' is not defined
>>> #对啊,没定义呢,才返回给他自己呢!

换个试试:

book1 = Book("use instance_method_create book instance")#正确的方法
print(book1)
book1 = Book.__init__(book1,"use instance_method_create book instance") 我先写出来book1么,再把他传进去
print(book1)
book2 = Book.class_method_create("use class_method_create book instance")
book3 = Book.static_method_create("use static_method_create book instance")
print(book1.title)
print(book2.title)
print(book3.title)

<__main__.Book object at 0x03DBAED0>
None
Traceback (most recent call last):
  File "C:\Users\Administrator\Desktop\FunandWay.py", line 23, in <module>
    print(book1.title)
AttributeError: 'NoneType' object has no attribute 'title'
#但是结果告诉我们,他没有返回来,是个“None”

仔细想想是不是他本身是不能写出来的!因为他已经不是那个他:

book1 = Book("use instance_method_create book instance")#正确的方法
print(book1,id(book1))
book1 = Book.__init__(book1,"use instance_method_create book instance")
print(book1,id(book1))
book2 = Book.class_method_create("use class_method_create book instance")
book3 = Book.static_method_create("use static_method_create book instance")
print(book1.title)
print(book2.title)
print(book3.title)
#output:
<__main__.Book object at 0x03A3AE90> 61058704
None 1554763724
Traceback (most recent call last):
  File "C:\Users\Administrator\Desktop\FunandWay.py", line 23, in <module>
    print(book1.title)
AttributeError: 'NoneType' object has no attribute 'title'
>>> 

地址都变了!也就是这个self我们就这么认为吧!哈哈!这个就记住吧!大家有什么好的方法吗?欢迎评论!

posted @ 2020-04-15 16:54  落月_YU  阅读(227)  评论(0编辑  收藏  举报