Python Learning-Object oriented 3

Object-oriented Other related one, isinstance (object,class_or_type_or_tuple)

Object that checks if object is Class_or_type_or_tuple

class Foo (object):     Pass  = Foo ()if  isinstance (obj,foo):    print('Yes ' ' )else:    print('No')

Second, Issubclass (c,b)

Check if C is a subclass of B

class B (object):     Pass class C (B):     Pass Print (Issubclass (C, B))

Third, super ()

Methods to execute the parent class

instances, ordered dictionaries

classmydict (dict):def __init__(self): self.__li=[] Super (mydict,self).__init__()    def __setitem__(self, Key, value): Self.__li. Append (key) Super (mydict,self).__setitem__(key, value)def __str__(self): temp_list= []         forKeyinchSelf.__li: Temp_list.append ("\ '%s\ ':%s"% (key,self.__getitem__(key))) Temp_str="{"+",". Join (Temp_list) +"}"        returnTemp_strobj=mydict () obj['K1'] ='v1'obj['K2'] ='v2'Print(obj)

Iv. Exception Handling

Exception handling for all structures, including at least try...except ...

Try:    #Line-by- row execution of the main code snippet    Print(123)exceptValueError as ex:#executed when ValueError is detected    Print(ex)exceptException as ex:#Exception matches all the same    #executes when an error other than ValueError is detected    Print(ex)Else:    #executes when the main code block finishes executing    Passfinally:    #regardless of whether the main code block has an error, execute    Pass

Proactively triggering exceptions

Try :     Raise Exception (' active error ')except  Exception as E:    Print (e)

Custom exceptions

 class   MyException (Exception):  Span style= "color: #0000ff;" >def  __init__   (self, msg): Self.message /span>= msg  __str__   return   Self.message  try  :  raise  myexception ( "  proactive wrong custom error   )    MyException as E:  print  (E) 

Assertion

# report assertionerror error when expression after assert is True assert 1 = = 1assert 1 = = 2

V. Design model of a single case model

Simple interest mode exists to ensure that only a single instance exists in the current memory, avoiding memory waste

classConnectpool (object):__pool=Nonedef __init__(self):Pass@staticmethoddefGet_pool ():if  notConnectpool.__pool: Connectpool.__pool=Connectpool ()returnConnectpool.__poolobj1=Connectpool.get_pool () obj2=Connectpool.get_pool ()Print(OBJ1,OBJ2)

Python Learning-Object oriented 3