from math import pi
class Circle:
def __init__(self,r):
self.r = r
def area(self):
return pi*self.r**2
def perimeter(self):
return 2*pi*self.r
c1 = Circle(5)
print(c1.area()) #78.53981633974483
print(c1.perimeter()) #31.41592653589793
圆形类
from math import pi
class Ring:
def __init__(self,r1,r2):
if r1>=r2:
self.outer = r1
self.inner = r2
else:
self.inner = r1
self.outer = r2
def area(self):
return pi * self.outer ** 2 - pi * self.inner ** 2
def perimeter(self):
return 2 * pi * self.outer + 2 * pi * self.inner
r1 = Ring(5,2)
print(r1.area()) #65.97344572538566
print(r1.perimeter()) #43.982297150257104
圆环类
from math import pi
class Cylinder:
def __init__(self,r,h):
self.r = r
self.h = h
def area(self):
c_area = pi * self.r**2
rec_area = 2 * pi *self.r * self.h
return c_area*2 + rec_area
def volume(self):
c_area = pi * self.r ** 2
return c_area*self.h
c1 = Cylinder(5,8)
print(c1.area()) #408.4070449666731
print(c1.volume()) #628.3185307179587
圆柱类
什么是耦合?
模块间的依赖性就是耦合,两个功能函数之间的依赖程度
紧耦合:紧耦合就是模块或者系统之间关系太紧密,存在相互调用。紧耦合系统的缺点在于更新一个模块的结果导致其它模块的结果变化,难以重用特定的关联模块。
松耦合通讯机制提供了紧耦合机制所没有的许多优点,并且它们有助于降低客户端和远程服务之间的依赖性。
类的组合
from math import pi
class Circle:
def __init__(self,r):
self.r = r
def area(self):
return pi*self.r**2
def perimeter(self):
return 2*pi*self.r
c= Circle(5)
print(c.area()) #78.53981633974483
print(c.perimeter()) #31.41592653589793
# 圆环类
class Ring:
def __init__(self,r1,r2):
c1 = Circle(r1)
c2 = Circle(r2)
if r1>=r2:
self.outer = c1 # 组合
# self.outer.area() # c1.area()
self.inner = c2 # 组合
else:
self.inner = c1 # 组合
self.outer = c2 # 组合
def area(self):
return self.outer.area() -self.inner.area()
def perimeter(self):
return self.outer.perimeter() + self.inner.perimeter()
r = Ring(5,2)
print(r.area()) #65.97344572538566
print(r.perimeter()) #43.982297150257104
# 圆柱类
class Cylinder:
def __init__(self,r,h):
self.c = Circle(r) # 组合
self.h = h
def area(self):
c_area = self.c.area()
rec_area = self.c.perimeter() * self.h
return c_area*2 + rec_area
def volume(self):
c_area = self.c.area()
return c_area*self.h
C = Cylinder(5,8)
print(C.area()) #408.4070449666731
print(C.volume()) #628.3185307179587
组合
一个类的对象是另一个类对象的属性
圆形类的对象 是圆环类对象的outer属性的值
计算圆形相关数据的公式只和Circle类在一起
其余的用到公式的地方都是通过circle类来使用的
公式与其他类之间的关系是一个“松耦合”关系
class Date:
def __init__(self,year,month,day):
self.year = year
self.month = month
self.day = day
def date(self):
return '%s-%s-%s'%(self.year,self.month,self.day)
#
class Student:
def __init__(self,name,num,birth,in_shcool,start_day):
self.name = name
self.num = num
self.birth = birth # 组合
self.in_school = in_shcool # 组合
self.start_day = start_day # 组合
d1 = Date(1999,10,27)
d2 = Date(2019,1,9)
d3 = Date(2019,2,9)
alex = Student('alex',10086,d1,d2,d3)
print(alex.birth.year) #1999
print(alex.birth.month) #10
print(alex.birth.day) #27
print(alex.birth.date()) #1999-10-27
alex.start_day.month +=1
print(alex.start_day.date()) #2019-3-9
学生类与日期类
class Student:
def __init__(self,name,num,course):
self.name = name
self.num = num
self.course = course
class Course:
def __init__(self,name,price,period):
self.name = name
self.price = price
self.period = period
python = Course('python',25000,'6 months')
s1 = Student('alex',10085,python)
s2 = Student('taibai',10084,python)
print(s1.__dict__) #{'name': 'alex', 'num': 10085, 'course': <__main__.Course object at 0x000001EB9FA5D9E8>}
print(s1.course.price) #25000
python.price = 30000
python.period = '7 months'
print(s2.course.period) #7 months
学生类与课程类