python 中exception，class学习

python 中exception，class 学习

instroduction:

Object2 = Object1 ( like java)

if Object1 is class object , then copy by reference;

if Object1 is basic type, then copy by value

1. exception

主要结构：

try:

exception ValueError:

exception ZeroDivisionError:

exception NameError:

exception TypeError:

exception:

finally:

2. custom exception

class Error(Exception):
pass

def MyError(Error):
def __init__(self,value):
print value
self.value = value
def __str__(self):
return repr(self.value)

3. class

class Bird:
number = 0
def __init__(self,name):
self.name = name
print 'Initializing %s' % self.name
def __del__(self):
print 'del',self.number
def fly(self):
print 'fly %d' % self.number
def add(self):
self.number = self.number + 1
def sub(self):
self.number = self.number - 1
class Sparrow(Bird):
def __init__(self,name,alias):
Bird.__init__(self,name)
self.alias = alias
print 'alias is %s ' % self.alias
def fly(self):
print 'Sparrow fly %s' % self.alias

description:

constructor: __init__

destructor:__del__

static data: number

4. file input/output

cPickle or pickle: store the object consistently