day6-python-面向对象

class f1:
    def __init__(self,a1,b1,c1):
        self.a1 = a1
        self.a2 = b1
        self.a3 = c1

    def select(self,sql):
        print(self.a1,self.a2,self.a3,sql)
    def add(self,sql):
        print(sql)
#实例化的时候自动执行类的__init__构造方法
obj = f1(‘1‘,‘2‘,‘3‘)
obj.host = ‘abc.com‘
obj.username = ‘alex‘
obj.pwd = ‘123‘
#当某些函数拥有相同参数时，使用面向对象
obj.select(‘select * from A‘)
obj.add(‘create table from A‘)
>>>1 2 3 select * from A
>>>create table from A

 1 class c1:
 2     def __init__(self,name,obj):
 3         self.name = name
 4         self.obj = obj
 5 
 6 class c2:
 7     def __init__(self,name,age):
 8         self.name = name
 9         self.age = age
10     def show(self):
11         print(self.name)
12 
13 c2_obj = c2(‘bb‘,18)
14 #将c2_obj当作参数传入obj，则c1_obj.obj=c2_obj  c2_obj.show = c1_obj.obj.show()
15 c1_obj = c1(‘aa‘,c2_obj)
16 c1_obj.obj.show()
17 >>>bb

 1 class F1:#父类，基类
 2     def show(self):
 3         print(‘show‘)
 4     def foo(self):
 5         print(self.name)
 6 
 7 class F2(F1):#子类，派生类
 8     def __init__(self,name):
 9         self.name = name
10     def bar(self):
11         print(‘bar‘)
12     def show(self):
13         print(‘F2.show‘)
14 #继承相当于将F1的方法放到F2中，
15 obj = F2(‘alex‘)
16 obj.foo()
17 #两个类中有相同方法时，自身的方法优先级高
18 obj.show()
19 >>>alex
20 >>>F2.show

 1 class f1():
 2     def c1(self):
 3         print(‘c1‘)
 4 class f2(f1):
 5     def c2(self):
 6         print(‘c2‘)
 7 class f3(f2):
 8     def c3(self):
 9         print(‘c3‘)
10 
11 class f5():
12     def c2(self):
13         print(‘c5‘)
14 class f4(f3,f5):
15     def c4(self):
16         print(‘c4‘)
17 #当子类有两个类时，优先从左边分支寻找，左边分支找到头之后找右边
18 obj =f4()
19 obj.c2()
>>>c2