面向对象中类的成员

Posted 2020-08-02 粗哥记事

   字段:
      静态字段
      普通字段
      PS:静态字段代码加载时候，已经创建

   方法
      所有的方法属于类
      1、普通方法：至少一个self，对象执行
      2、静态方法：任意参数，    类执行（对象执行）
      3、类方法  ：至少一个cls， 类执行（对象执行）
   属性
      不论不类的东西
      具有方法的写作形式，具有字段访问形式

        def func(arg):
            print(arg)

        func(1)
        func("alex")
        func([11,22,33])



        C#/Java

        def func(int arg):#指定类型
            print(arg)


        func(123)
        func("alex")  #报错



        如何实现?

        class A:
            pass

        class B(A):
            pass

        class C(A):
            pass


        #arg参数,必须是A类型或A的子类型

        def func(A arg):
            print(arg)


        obj = B()
        obj = C()
        obj = A()

        func(obj)


    字段



    class Foo:
        CC = 123  #静态字段

        def __init__(self):
            self.name = ‘alex‘  #普通字段


        def show(self):
            print(self.name)
字段:
一般情况下,自己访问自己的字段

规则:
    普通字段只能用对象访问
    静态字段用类访问(万不得已的时候才可以使用对象访问)


方法:
    普通方法  至少一个self,  对象执行
    静态方法    任意参数, 类执行 (对象执行)
    类方法     至少一个cls 类执行 (对象执行)



    @staticmethod
    def f1(a1,a2):
        print(a1,a2)

    def f2(cls):
        print(cls)    #cls类名,()创建对象

obj = Province(‘beijing‘)

obj.show


属性  

class Pager:

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

   @property   #属性的获取
   def all_pager(self):
      a1, a2 = divmod(self.all_count, 10)
      if a2 == 0:
         return a1
      else:
         return a1 +1

   @all_pager.setter
   def all_pager(self, value):
      print(value)
   @all_pager.deleter:
      print(‘del all_pager‘)



p = Pager(101)

#p.all_count#字段
print(p.all_count)

p.all_count = 102

del p.all_count


ret = p.all_pager

print(ret)

p.all_pager = 111


del p.all_pager



属性2



class Pager:

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

    def f1(self):
        pass

    def f2(self):
        pass

    def f3(self):
        pass

    foo = property(fget=f1,fset=f2,fdel=f3)

p = Pager(101)

result = p.foo
print(result)

p.foo = ‘alex‘

del p.foo



成员修饰符


    私有:
        只能类自己本身成员内部访问


    公有
        pass



class Foo:

    #构造方法
    def __init__(self, name, age)
        self.name = name
        self.age = age

    #析构方法
    def __del__(self):
        pass


    def __call__(self):
        print(‘call‘)

    def __str__(self):
        return "%s - %s" %(self.name, self.age)



obj = Foo()

obj()#对象() 执行call方法

#Foo()()


obj1 = Foo(‘alex‘,77)

ret = str(obj1)   #str 方法

print(ret)

#__dict__获取对象中封装的数据
ret = obj1.__dict__

print(ret)



def __getitem__(self, item):


    #item.start,item.stop,item.step
    return 123

def __setitem__(self, key, value):
    print(‘setitem‘)

def __delitem__(self, key):
    print(‘del item‘)

dic = {"k1":123} #dic = dict(k1=123)

dic[‘k1‘] #dic()

dic[‘k1‘] = 123

del dic[‘k1‘]




#!/usr/bin/env python
# -*- coding:utf-8 -*-
# Author:Alex Li
class Foo:

    # 构造方法
    def __init__(self, name,age):
        self.name = name
        self.age = age

    # 析构方法
    def __del__(self):
        pass

    def __call__(self):
        print(‘call‘)

    def __str__(self):
        return "%s - %d" %(self.name, self.age)

    def __add__(self, other):
        temp = "%s - %d" %(self.name,other.age)
        return temp

    def __getitem__(self, item):
        # print(type(item),item)
        # item.start   item.stop  item.step
        print(type(item))
        return 123

    def __setitem__(self, key, value):
        # key.start   key.stop  key.step
        print(type(key),type(value))

    def __delitem__(self, key):
        # key.start   key.stop  key.step
        print(type(key))


obj = Foo(‘alex‘, 73)
# obj() # call
# 语法对应关系
# ret1 = obj[‘ad‘]
ret2 = obj[1:4:2]
obj[1:4] = [11,22,33,44,66]
del obj[1:4]
# print(ret)
# obj[‘k1‘] = 111
# del obj[‘k1‘]

# dic = {‘k1‘: 123} # dic = dict(k1=123)
# dic[‘k1‘] # dic()
# dic[‘k1‘] = 123
# del dic[‘k1‘]



obj = Foo()
obj() # 对象() 执行call
# Foo()()

obj1 = Foo(‘alex‘, 73)
obj2 = Foo(‘eric‘, 84)
# 获取对象中封装的数据
ret = obj1.__dict__
print(ret)

# print(Foo.__dict__)

# print(obj1)
# print(obj2)

# ret = str(obj1)
# print(ret)

# ret = obj1 + obj2
# print(ret)
# __dict__



class C1:
    def f1(self):
        print(‘c1,f1‘)
        return 123


class C2(C1):
    def f1(self):
        # 主动执行父类f1方法
        ret = super(C2, self).f1()

        print(‘c2.f1‘)

        return ret

        # C1.f1(self)


obj = C2()

obj.f1()




#有序字典

class MyDict(dict):

    def __init__(self):
        self.li = []
        super(MyDict, self).__init__()

    def __setattr__(self, key, value):
        self.li.append(key)
        super(MyDict, self).__setattr__()

    def __str__(self):
        temp_list = []
        for key in self.li:
            value = self.get(key)
            temp_list.append("‘%s‘:%s‘" %(key,value,))
        temp_str = "{" + ",".join(temp_list) + "}"
        return temp_str

obj = MyDict()
obj[‘k1‘] = 123
obj[‘k2‘] = 456

print(obj)

"""


class Foo:

    instance = None

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

    @classmethod
    def get_instance(cls):

        #cls类名
        if cls.instance:
            return cls.instance
        else:
            obj = cls(‘alex‘)
            cls.instance = obj
            return obj


obj1 = Foo.get_instance()
print(obj1)
obj2 = Foo.get_instance()
print(obj2)