Python抽象及异常处理

标签：其他   attribute   traceback   method   style   不同类   程序崩溃   init   文件   

#面向对象:多态、封装、继承
#1 多态：意味着即使不知道变量所引用的对象类型是什么，还是能对他进行操作，而且也会根据他的不同类型表现出不同的行为
#多态和方法

from random import choice
x = choice([‘Hello World‘,[‘1‘,‘1‘,‘1‘,‘2‘,‘3‘]])
print(x)
print(x.count(‘1‘))#1出现的次数 不需要检测类型 只需要知道有conut这个方法
#多态的多种形式：+运算对字符串、数字起作用

#2 封装对全局作用域中的其他区域隐藏多余信息
#3 继承：不想代码重复 使用原来的代码
#4 类
#创建类
_metaclass_= type
class Person:
    def setname(self,name):
        self.name = name
    def getname(self):
        return self.name
    def greet(self):
        print("Hello I am %s"%self.name)
#调用类
foo = Person()
bar = Person()
foo.setname("1234567")
bar.setname("7891213")
foo.greet()
bar.greet()
print(foo.name,bar.name)
#-------------------------输出结果----------------------------------#
"""
C:\python3.7\python.exe D:/Python-Test/qiubai/qiubai/Test6.py
Hello World
0
Hello I am 1234567
Hello I am 7891213
1234567 7891213
"""

#特性、函数、方法
class Class:
    def method(self):
        print("I am self")
def fuction():
    print("I don‘t...")

obj = Class()
obj.method()
obj.method = fuction # 特性绑定到一个普通的函数上
obj.method()

test = obj.method #test变量引用绑定方法上
test()

#-------------------------输出结果----------------------------------#
"""
I am self
I don‘t...
I don‘t..
"""

#私有特性：为了让特性和方法变成私有（外部不能访问），只要在名字前加上双下划线
#指定超类
class Filter:
    def init(self):
        self.blocked=[]
    def filter(self,test):
        return [x for x in test if x not in self.blocked]
    def _test(self):
        print("我是私有的")
class ChildFilter(Filter):#指定超类 ChildFilter为Filter的子类
    def init(self):
        print("我是子类 正在重写父类方法")
        self.blocked=[‘as‘]
f = Filter()
f.init()
print(f.filter([1,2,3]))

f1 = ChildFilter()
f1.init()
print(f1.filter([1,23,56]))

#-------------------------输出结果----------------------------------#
"""
C:\python3.7\python.exe D:/Python-Test/qiubai/qiubai/Test6.py
[1, 2, 3]
我是子类 正在重写父类方法
[1, 23, 56]
"""


#捕获异常
try:
    x = 5
    y = 0
    print(x/y)
except ZeroDivisionError:
    print("分母不能为0")
#-------------------------输出结果----------------------------------#
"""
C:\python3.7\python.exe D:/Python-Test/qiubai/qiubai/Test6.py
分母不能为0
"""

# raise
class MuffledCalculator:
    muffed = False
    def calc(self,expr):
        try:
            return eval(expr)
        except ZeroDivisionError:
            if self.muffed:
                print("Division is zero by illegal")
            else:
                raise #
cal = MuffledCalculator()
print(cal.calc(‘10/2‘))
cal.muffed = True #打开屏蔽机制
print("hehehe-->",cal.calc(‘10/0‘))
#-------------------------输出结果----------------------------------#
"""
C:\python3.7\python.exe D:/Python-Test/qiubai/qiubai/Test6.py
分母不能为0
5.0
Division is zero by illegal
hehehe--> None
"""

#用一个块捕捉两个异常
try:
    x = input("input your first num:")
    y = input("input your second num:")
    print(x/y)
except(ZeroDivisionError,TypeError,NameError).e:
    print("Your Num were bug")
    print(e)


while True:
    try:
        x = int(input("input your first num:"))
        y= int(input("input your second num:"))
        value = x/y
        print(value)
    except Exception.e:
        print("Exception ",e)
        print("try again")
    else:
        break


"""
#-------------------------输出结果----------------------------------#
C:\python3.7\python.exe D:/Python-Test/qiubai/qiubai/Test6.py
input your first num:10input your second num:33.3333333333333335C:\python3.7\python.exe D:/Python-Test/qiubai/qiubai/Test6.pyinput your first num:10input your second num:0Traceback (most recent call last):  File "D:/Python-Test/qiubai/qiubai/Test6.py", line 145, in <module>    value = x/yZeroDivisionError: division by zeroDuring handling of the above exception, another exception occurred:Traceback (most recent call last):  File "D:/Python-Test/qiubai/qiubai/Test6.py", line 147, in <module>    except Exception.e:AttributeError: type object ‘Exception‘ has no attribute ‘e‘"""while True:    try:        x = int(input("input your first num:"))        y= int(input("input your second num:"))        value = x/y        print(value)    except:        print("try again")    else:#只有程序没有异常情况才会退出 只要错误发生，程序会不断重新要求输入        break"""#-------------------------输出结果----------------------------------#C:\python3.7\python.exe D:/Python-Test/qiubai/qiubai/Test6.pyinput your first num:10input your second num:0try againinput your first num:10input your second num:33.3333333333333335"""#Finally:x = Nonetry:    x = x / 0finally:#通常用于关闭文件或网络套接字    print(‘Clean up .....‘)    del x #程序崩溃之前 对于x的变量清理    """C:\python3.7\python.exe D:/Python-Test/qiubai/qiubai/Test6.pyClean up .....Traceback (most recent call last):  File "D:/Python-Test/qiubai/qiubai/Test6.py", line 203, in <module>    x = x / 0TypeError: unsupported operand type(s) for /: ‘NoneType‘ and ‘int‘"""

Python抽象及异常处理

标签：其他   attribute   traceback   method   style   不同类   程序崩溃   init   文件   

原文地址：http://www.cnblogs.com/acer-haitao/p/7304903.html