python django working of object copy technique

python django working of object copy technique

class MyClass:

   def __init__(self, name):
       self.amount = 100
       self.name = name

   def test(self):
       print "test"


m1 = MyClass('SAJU')

print "\n-------m1---------", m1
print "\n--------dir(m1)----------", dir(m1)
print "\n--------vars(m1)----------", vars(m1)
print "\n---------m1.__dict__-----------------", m1.__dict__
print "\n----------m1.__class__.__name__----------------", m1.__class__.__name__
print "\n===============================================1"


class EmptyClass:
   pass

e1 = EmptyClass()

print "\n-------e1---------", e1
print "\n--------dir(e1)----------", dir(e1)
print "\n--------vars(e1)----------", vars(e1)
print "\n---------e1.__dict__-----------------", e1.__dict__
print "\n----------e1.__class__.__name__----------------", e1.__class__.__name__
print "\n-------isinstance(e1, EmptyClass)--------", isinstance(e1, EmptyClass)
print "\n-------isinstance(e1, MyClass)--------", isinstance(e1, MyClass)
print "\n===============================================2"

e1.__class__ = m1.__class__

print "\n-------e1---------", e1
print "\n--------dir(e1)----------", dir(e1)
print "\n--------vars(e1)----------", vars(e1)
print "\n---------e1.__dict__-----------------", e1.__dict__
print "\n----------e1.__class__.__name__----------------", e1.__class__.__name__
print "\n-------isinstance(e1, EmptyClass)--------", isinstance(e1, EmptyClass)
print "\n-------isinstance(e1, MyClass)--------", isinstance(e1, MyClass)
print "\n===============================================3"

e1.__dict__.update(m1.__dict__) 

print "\n-------e1---------", e1
print "\n--------dir(e1)----------", dir(e1)
print "\n--------vars(e1)----------", vars(e1)
print "\n---------e1.__dict__-----------------", e1.__dict__
print "\n----------e1.__class__.__name__----------------", e1.__class__.__name__
print "\n-------isinstance(e1, EmptyClass)--------", isinstance(e1, EmptyClass)
print "\n-------isinstance(e1, MyClass)--------", isinstance(e1, MyClass)
print "\n===============================================4"



OUTPUT
=======
-------m1--------- <__main__.myclass>

--------dir(m1)---------- ['__doc__', '__init__', '__module__', 'amount', 'name', 'test']

--------vars(m1)---------- {'amount': 100, 'name': 'SAJU'}

---------m1.__dict__----------------- {'amount': 100, 'name': 'SAJU'}

----------m1.__class__.__name__---------------- MyClass

===============================================1

-------e1--------- <__main__.emptyclass>

--------dir(e1)---------- ['__doc__', '__module__']

--------vars(e1)---------- {}

---------e1.__dict__----------------- {}

----------e1.__class__.__name__---------------- EmptyClass

-------isinstance(e1, EmptyClass)-------- True

-------isinstance(e1, MyClass)-------- False

===============================================2

-------e1--------- <__main__.myclass>

--------dir(e1)---------- ['__doc__', '__init__', '__module__', 'test']

--------vars(e1)---------- {}

---------e1.__dict__----------------- {}

----------e1.__class__.__name__---------------- MyClass

-------isinstance(e1, EmptyClass)-------- False

-------isinstance(e1, MyClass)-------- True

===============================================3

-------e1--------- <__main__.myclass>

--------dir(e1)---------- ['__doc__', '__init__', '__module__', 'amount', 'name', 'test']

--------vars(e1)---------- {'amount': 100, 'name': 'SAJU'}

---------e1.__dict__----------------- {'amount': 100, 'name': 'SAJU'}

----------e1.__class__.__name__---------------- MyClass

-------isinstance(e1, EmptyClass)-------- False

-------isinstance(e1, MyClass)-------- True

===============================================4

python django howto class name as string

python django how to get class name of an object as string

>>> l = []
>>>
>>> l.__class__.__name__
'list'
===================
>>> t = ()
>>>
>>> t.__class__.__name__
'tuple'
===================
>>> d = {}
>>>
>>> d.__class__.__name__
'dict'
===================
>>> i = int(4)
>>>
>>> i
4
>>> i.__class__.__name__
'int'
===================
>>> f = float(4)
>>>
>>> f
4.0
>>>
>>> f.__class__.__name__
'float'
-------------------------
>>> class Test:
...     pass
...
>>>
>>>
>>> t = Test()
>>>
>>> t.__class__.__name__
'Test'
===================

main uses of python __class__

main uses of python __class__

>>> l = [2,4]

>>> l
[2, 4]

>>> l.__class__
type 'list'>

>>> l2 = l.__class__()

>>> l2
[]

>>> l.__class__.__name__
'list'

=====================

>>> l = [2,4]

>>> l
[2, 4]

* Return class (class object) of object l.

>>> l.__class__
type 'list'>

* Creating object of that class (class object) by putting "()" at the end.

>>> l2 = l.__class__()

>>> l2
[]

* To get class name of a python object

>>> l.__class__.__name__
'list'

===================== following are equal

>>> l.__class__
type 'list'>

>>> type(l)
type 'list'>

===================== following are equal

>>> l2 = l.__class__()
>>> l2
[]

>>> l2 = type(l)()
>>> l2
[]

=====================

* You can get the class (class object) of any object by calling "type" on it.

>>> type(l)
type 'list'>

* we can create object of that class (class object) by putting "()" at the end.

>>> lt = type(l)

>>> lt
type 'list'>

>>> lt()  <---------"()" at the end.
[]

=====================  

python defining special methods __eq__ and __le__ on a class

python defining special methods __eq__ and __le__ on a class

class A:
   
    def __init__(self, num):
        self.num = num

    def __add__(self, second_num):
        return self.num + second_num

    def __eq__(self, second_num):
        if self.num == second_num:
            print "\nNumbers are equal"
        else:
            print "\nNumbers are not equal"
       
    def __le__(self, second_num):
        if self.num <= second_num:
            print "\n"+str(self.num)+" is less than or equal to "+str(second_num)
        else:    
            print "\n"+str(self.num)+" is grater than "+str(second_num)           

a1 = A(10)

print "-------a1 + 10-------", a1 + 40

print "-------a1 == 10-------", a1 == 10

print "-------a1 == 10-------", a1 == 20

print "-------a1 <= 30 -------", a1 <= 30

print "-------a1 <= 5 -------", a1 <= 5



OUTPUT
=======
-------a1 + 10------- 50
-------a1 == 10-------
Numbers are equal
None
-------a1 == 10-------
Numbers are not equal
None
-------a1 <= 30 -------
10 is less than or equal to 30
None
-------a1 <= 5 -------
10 is grater than 5
None

python defining special method __add__ on a class

python defining special method __add__ on a class

======================== 1


class A:
   
    def __init__(self, num):
        self.num = num

    def __add__(self, second_num):
        return self.num + second_num
               

a1 = A(10)

print "-------a1 + 10-------", a1 + 40
print "-------a1 + a1-------", a1 + a1


OUTPUT
=======
-------a1 + 10------- 50  <--------
-------a1 + a1-------
Traceback (most recent call last):
  File "sp.py", line 16, in 
    print "-------a1 + a1-------", a1 + a1
  File "sp.py", line 10, in __add__
    return self.num + second_num
TypeError: unsupported operand type(s) for +: 'int' and 'instance'


======================== 2

class A:
   
    def __init__(self, num):
        self.num = num

    def __add__(self, second_object):
        return self.num + second_object.num
               

a1 = A(10)

print "-------a1 + a1-------", a1 + a1
print "-------a1 + 10-------", a1 + 40


OUTPUT
=======
-------a1 + a1------- 20   <--------
-------a1 + 10-------
Traceback (most recent call last):
  File "sp.py", line 16, in 
    print "-------a1 + 10-------", a1 + 40
  File "sp.py", line 10, in __add__
    return self.num + second_object.num
AttributeError: 'int' object has no attribute 'num'



======================== 3

class a:
    def __init__(self):
        pass

a1 = a()

print "-------a1 + a1-------", a1 + a1


OUTPUT
========
test@saju-laptop:~/Desktop$ python sp.py
-------a1 + a1-------
Traceback (most recent call last):
  File "sp.py", line 10, in 
    print "-------a1 + a1-------", a1 + a1
TypeError: unsupported operand type(s) for +: 'instance' and 'instance'


======================== 4

class A:
    def __init__(self):
        pass

    def __add__(self, second_item):
        print "\n-------in------__add__-------"
        print "\n-------first item-------", self
        print "\n-------second item------", second_item
        #Note: Here items first and second are same(same object 'a1' of class 'A')

a1 = A()

print "--------a1---------", a1

print "\n\***********\n"

print "-------a1 + a1-------", a1 + a1

print "\n\***********\n"

print "---------a1.__add__(a1)------------", a1.__add__(a1)

#Note: Here "a1 + a1" and  "a1.__add__(a1)" are same.




OUTPUT
=======
--------a1--------- <__main__.a>

\***********

-------a1 + a1-------
-------in------__add__-------

-------first item------- <__main__.a>

-------second item------ <__main__.a>
None

\***********

---------a1.__add__(a1)------------
-------in------__add__-------

-------first item------- <__main__.a>

-------second item------ <__main__.a>
None


======================== 5

class A:
   
    def __init__(self):
        pass

    def __add__(self, second_item):
        print "\n-------in------__add__-------"
        print "\n-------first item-------", self
        print "\n-------second item------", second_item
        #Note: Here items first 'a1' and second 'a2' are different

a1 = A()
a2 = A()

print "--------a1---------", a1
print "--------a2---------", a2

print "\n\***********\n"

print "-------a1 + a2-------", a1 + a2

print "\n\***********\n"

print "---------a1.__add__(a2)------------", a1.__add__(a2)

#Here "a1 + a2" and  "a1.__add__(a2)" are same.


OUTPUT
=======
--------a1--------- <__main__.a>
--------a2--------- <__main__.a>

\***********

-------a1 + a2-------
-------in------__add__-------

-------first item------- <__main__.a>

-------second item------ <__main__.a>
None

\***********

---------a1.__add__(a2)------------
-------in------__add__-------

-------first item------- <__main__.a>

-------second item------ <__main__.a>
None


========================

python django defining __getitem__ on a class

python django defining __getitem__ on a class

# defining __getitem__ on a class make it iterable in python?
# cb[0] is the same as cb.__getitem__(0)

#############################################1

class Test3:

    Data = {'name':'saju', 'sex':'male'}   

    def __init__(self):
        print "----in----__init__----"

    def __getitem__(self, item1):
        return self.Data[item1]


t3 = Test3()
print t3['name']
print t3['sex']


# OUTPUT
# ======
# ----in----__init__----
# saju
# male

#############################################2

class Test1:

    def __init__(self):
        print "----in----__init__----"

    def __getitem__(self, item1):
        print "-----in-----__getitem__-----", item1
        if item1==5:
            raise Exception('End')#For stop iteration (otherwise it will go to a loop)


t1 = Test1()

print "=============="

t1['saju'] #<----------IMP
t1.__getitem__('saju')

print "=============="
for x in t1:
    pass

# OUTPUT
# ======
# ----in----__init__----
# ==============
# -----in-----__getitem__----- saju
# -----in-----__getitem__----- saju
# ==============
# -----in-----__getitem__----- 0
# -----in-----__getitem__----- 1
# -----in-----__getitem__----- 2
# -----in-----__getitem__----- 3
# -----in-----__getitem__----- 4
# -----in-----__getitem__----- 5
# Traceback (most recent call last):
#   File "getitem.py", line 26, in 
#     for x in t1:
#  File "getitem.py", line 15, in __getitem__
#     raise Exception('End')#For stop iteration (otherwise it will go to a loop)
# Exception: End


#############################################3

class Test2:

    def __init__(self):
        print "----in----__init__----"

    def __getitem__(self, item1, item2=0):
        print "-----in-----__getitem__-----", item1, item2
        if item1==5:
            raise Exception('End')#For stop iteration (otherwise it will go to a loop)


t2 = Test2()

print "=============="

t2['saju'] #<----------IMP
t2.__getitem__('saju','1000')

print "=============="

for x in t2:
    pass

# OUTPUT
# ======
# ----in----__init__----
# ==============
# -----in-----__getitem__----- saju 0
# -----in-----__getitem__----- saju 1000
# ==============
# -----in-----__getitem__----- 0 0
# -----in-----__getitem__----- 1 0
# -----in-----__getitem__----- 2 0
# -----in-----__getitem__----- 3 0
# -----in-----__getitem__----- 4 0
# -----in-----__getitem__----- 5 0
# Traceback (most recent call last):
#   File "getitem.py", line 72, in 
#     for x in t2:
#   File "getitem.py", line 60, in __getitem__
#     raise Exception('End')#For stop iteration (otherwise it will go to a loop)
# Exception: End

#############################################

Python calculate time taken to execute a function

Python calculate time taken to execute(run) a code or function or script.

>>> now = time.time()

>>> content1 = Myclass().content()  <---- do some works

>>> time.time() - now
22.43316888809204  <-------time taken to do that works

python if in operation with string

python "if in" operation with string

>>> name = 'smithjohnannaivan'
>>> 
>>> if 'john' in name:
...     print '---ok-----'
... 
---ok-----
 >>>