Builtin attributes of a class

Builtin attributes of a class :

• For each and every class in python some attributes/properties are going to be added automatically by the python interpreter.

• the attributes which are added by the python interpreter are known as builtin attributes/properties.

_ _dict_ _

_ _doc_ _

_ _name_ _

_ _module_ _

_ _bases_ _

_ _weakref_ _

class Test:

    """sample class for builtin attributes"""

    a=100

    def m1(self):

        print("in m1 of test")

print(Test.a)

t1=Test()

t1.m1()

print(Test.__doc__)

print(Test.__dict__)

print(Test.__name__)

print(Test.__module__)

print(Test.__bases__)

print(Test.__weakref__)

100

in m1 of test

sample class for builtin attributes

{'m1': <function Test.m1 at 0x0000000000761400>, 'a': 100, '__doc__': 'sample class for builtin attributes', '__module__': '__main__', '__weakref__': <attribute '__weakref__' of 'Test' objects>, '__dict__': <attribute '__dict__' of 'Test' objects>}

Test

__main__

(<class 'object'>,)

<attribute '__weakref__' of 'Test' objects>

Methods:

• It is possible to define two kinds of methods with-in a class that can be called without an instance.

Class Method:

• A class method takes cls as first parameter.
• A class method can access or modify class state.
• We use @classmethod decorator in python to create a class method.
• We generally use class method to create factory methods.

Syntax:

class C(object):

    @classmethod

    def fun(cls, arg1, arg2, ...):

       ........................

       ........................

       ........................

Static Method:

• A static method needs no specific parameters.
• A static method can’t access or modify it.
• We use @staticmethod decorator to create a static method in python.
• We generally use static methods to create utility functions.

Syntax:

class C(object):

    @staticmethod

    def fun( arg1, arg2, ...):

       ....................

       ....................

       ....................

Example:

class Test(object):

    x=20

    def m1(self):

        print"hai,i am in instance method"

        print(Test.x)

 

    @classmethod

    def m2(cls):

        print "hai,i am in class method"

        print(Test.x)

 

    @staticmethod

    def m3():

        print "hai,i am in static method"

        print(Test.x)

 

Test.m2()

Test.m3()

Test.m1()