Classes and Objects

 camelCase

PascalCase

class PascalCase # always

object = class()   to declare a object part of class and then perform functions

memory is alloted only after the above step

class ClassName:

    class_attribute1=value1

    attribute2=value2

object = ClassName()

object_attribute= value # updates individual value or add new value

object_attribute > class_attribule # more powerful(in times of calling them)

self-> gets automatically replaced with object name # to use within a func in class self.variable

object.fun()==class.fun(object) **

@staticmethod # written before def to make it as class.fun() # it is a decorator

def __init__(self, {can contain more variable})==it gets automatically run even without calling when a object is created.

eg. def __init__(self,a,b):

                self.a=a

                self.b=b

object=class(5,80)

the above is called a constructor and its arguments are written in object=class(arguments)

__method__ are called dunder method

types of function_names in a class:

attribute # normal

_attribute # normal used for human debugging

__attribute # saved as _classname__attribute()

dir(object) to check attributes

__name__ by default is equal to" __main__" or the name of module used 

self.attribute use only if defined in __init__ method else directly call variable.

object.variable == instance , class.variable

print(object.__dict__) shoes all instance attributes

@classmethod- def function(cls): cls.variable

anything can be written instead of self

creating a new object by function # class method as alternate constructor (like __init__)

@classmethod

    def new_object(cls,string):

        name,salary=string.split("-")

        return cls(name,salary)

help(ClassName)==show details

print(function)==output is return value of function

__repr__ direct calling eg print(variable)==print(repr(variable))

@property

def email(self):

    return self.name+"@gmail.com"

@email.setter

def email(self,given_email):

    # self.email=given_email show error as we can't directly change

    self.name=given_email.split('@')[0]

@function_name.deleter

    def function_name(self):

    del self.attribute1

    self.attribute2=None

use with if condition if ==none in .setter

del object.function_name  [which was used as property]    

from abc import ABCMeta or ABC(for py 3.4 or higher), abstractmethod

@abstractmethod 

class BaseClassName(metaclass=ABCMeta)/(ABC)

@abstractmethod

def function_name():

it makes sure that any child class derived from the base class need to have a function which is specified in base class.

INHERITANCE

class BaseClass1:

attribute1=value1

class BaseClass2:

attribute1=value1.1

attribute2=value2

class DerivedClass1(BaseClass1) # single inheritance

child > parents

class DerivedClass2(BaseClass1, BaseClass2) # multiple inheritance

baseclass1>baseclass2 so,

object=derivedclass1()

print(object.attribute1)==value1 because of order in parenthesis

super().function_name(arguments) # it is followed by common function syntax

the above method is written in derived above if common function between both .

first it do as per base function then derived function.

self.variable=var #instance

self.__class__.variable=var # change class attribute

the above can be done by using @classmethod and cls in place of self

@property # to male a function behave a property [  function()   .property   ]#also known as getter

@function_name[used under @property].setter then def function_name(self,variable) # object.function_name=val1

operator overloading using dunder . these are called by numerical operators

+ == __add__

* == __mul__

- == __sub__

/ == __truediv__

// == __floordiv__

__str__ == defines str(object) or direct calling

__len__ == defines len(object)