Python part2 v1

4-Jan-20 1
Python - II
Copyright (c) SunilOS ( RAYS )
Technologies
www.raystec.com
www.sunilos.com

Application
One application is made of multiple modules
A Module is a file with extension .py
A module can define functions, classes and variables.
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Module Module
Module Module
Application

Module
 Module is a file of .py extension
 Module may contain following
elements
o related functions
o related variables
o classes
 One .py file is a one Module
 Elements of one module can be
imported into another Module
variables
Functions
Module.py
class

UserService.py
 Following is UserService module which contains two methods add()
and update()
o def add( firstName, lastName ):
o print("Adding User")
o print('Name’,firstName, lastName)
o return
o def update( firstName, lastName ):
o print("Updating User")
o print('Name',firstName,lastName)
o return

TestUserService.py
 You can import a module by import statement in python
program. We are importing UserService.py module in
TestUserService.py file.
o import UserService
 Now you can use module functions:
o UserService.add("Ram" , "Sharma")
o UserService.update("Shyam" , "Sharma")

from … import statement
 You can import specific functions from a module using from … import
statement.
 TestUserModel.py may have following import statement
o from UserService import add,update
o add("Ram","Sharma")
o update("Shyam","Sharma")
 You can import all methods using * character
o from UserService import *

Module search path
 When you import a module, python interpreter searches module
in different directories in the following sequences:
o The current directory.
o If module is not found then searches each directory specified
in environment variable PYTHONPATH.
o If all fails then python checks the default path.
 You can set PYTHONPATH as per your app requirements
o set PYTHONPATH = c:pythonlib1;c:pythonlib2;

OOP
 Object Oriented Programming
 There are three key concepts of OOP
o Encapsulation: gather all related attributes and method.
o Inheritance: create expert classes
o Polymorphism: achieve dynamic behavior
 It achieves Modularity and Reusability
 One application is made of multiple objects at runtime

OOP Application Runtime
Application runtime is made of multiple objects
At runtime multiple objects collaborate to perform your
business operations
Application Runtime
Object Object Object
Object Object

Class; structure of an Object
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Realization
Realization
State/Variables
• currentGear
• Speed
• Color
Methods
• changeGear()
• accelerator()
• break()
• changeColor()
State/Variables
• name
• address
Methods
• changeName()
• changeAddress()
Structure
Real world entities based on
structure
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Class
 Class is the data structure that defines structure of an object.
 Class contains related attributes and methods.
 Each class is an EXPERT class.
 Class is a Noun.
 Classes represent real world entities such as:
o Person
o Account
o Shape

Real World Entities – More Classes
:Automobile
-color :String
-speed:int
-make:String
+$NO_OF_GEARS
+getColor():String
+setColor()
+getMake():String
+setMake()
+break()
+changeGear()
+accelerator()
+getSpeed():int
:Person
-name:String
-dob : Date
-address:String
+$AVG_AGE
+getName():String
+setName()
+getAdress():String
+setAddress()
+getDob (): Date
+setDob ()
+getAge() : int
:Account
-number:String
-accountType : String
-balance:double
+getNumber():String
+setNumber()
+getAccountType():String
+setAccountType()
+deposit ()
+withdrawal ()
+getBalance():double
+fundTransfer()
+payBill()
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An Expert never overlap responsibilities
Creator
Preserver
Destroyer
Trimurti
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Object
 An object is the variable of type Class.
 You can create multiple objects of a Class.
 When memory is allocated to an object, object becomes instance.
 Memory allocation process of an object is called instantiation.
Class
Object
Object
Object

Experts bring Modularity and Reusability
Copyright (c) SunilOS ( RAYS ) Technologies 154-Jan-20

Create a Class
 A class is defined by ‘class’ keyword which is followed by
class name.
o class Person:
o ‘Contains person info‘
 First line in the class is a string which describes information of
the class.
 Class contains following members
o Class variables (attributes)
o Instance variables (attributes)
o Methods
o Constructor
o Destructor

Person Class
 class Person:
 count = 0 #class variable
 def __init__(self): #Constructor
 self.name = "" #instance variable
 Person.count += 1
 def setName(self,n): #Method
 self.name = n

 def getName(self): #Method
 return self.name

Test Person
 Lets create two objects p1 and p2 of class Person
o p1 = Person() #instantiation
o p1.setName("Ram")
o p2.setName("Shyam")
 Print value of objects
o print(p1.name)
o print(p1.getName())
o print(Person.count)

Class Vs Instance (Object) attributes
 Class attributes are defined and
initialized outside methods
o class Person:
 count = 0
 Memory is allocated to class
variables only once in its lifetime
 Class variable is accessed with
class name
o print(Person.count)
 Instance attributes are defined and
initialized inside constructer
o class Person:
 def
__init__(self):
• self.name =“”
 For each instance separate memory
is allocated to instance variables
 whereas instance variable is called
with object name
o p1 = Person()
o print(p1.name)

Constructor
 Each class has one constructor defined by __init__() method
 It is executed when object is instantiated
o p1 = Person()
 It is used to initialize instance variables
 def __init__(self):
• self.name = “Ram”
• self.address = “Mumbai”
 First parameter self is passed to access current instance of the class
 Optionally you can pass additional parameter to initialize class attributes:
 def __init__(self):
• self.name = “Ram”
• self.address = “Mumbai”

Methods
 Method is a function defined by def keyword
 Methods perform business operations and can change value of
member attributes
o class Person:
o def setName(self,n):
o self.name = n
o def getName(self):
o return self.name
 First parameter self is passed to each method to access
instance variables
o p1 = Person()
o p1.setName("Ram")

Class Methods
 A class method is called with class name
o Math.max(5,10)
 Class method does not require self as first parameter
o class Math:
o def max( a, b):
o if(a > b):
o return a
o else:
o return b

Object
 An object is the variable of type Class. You can create multiple objects of a
Class.
 When memory is allocated to an object, object is called instance and process
called instantiation.
 Here are person instances
o p1.setName("Ram")
o p2.setName("Shyam")
 You can print memory address of an object using id() method.
o print('ID', id(p1) )

Destructor __del__
 An object is garbage collected when it becomes orphan.
 Destructor method is called before an object is garbage collected
and removed from memory.
 Destructor is defined by __del__() method.
o def __del__(self):
o className = self.__class__.__name__
o print ("Destroying ", className )

Method __str__
 Method __str__ is used to define string representation of an object.
o def __str__( self ):
o return ”%s" % (self.name)
 When you print an object then string returned by this function is printed:
o print(p1)
 Remove an object from memory using del keyword:
o del p1
o del p2

Class metadata
 You can print class information using following attributes:
o print (“Person.__doc__:", Person.__doc__)
o print ("Person.__name__:", Person.__name__)
o print ("Person.__module__:", Person.__module__)
o print ("Person.__bases__:", Person.__bases__)
o print ("Person.__dict__:", Person.__dict__)
 Object dictionary
o print (p1.__dict__)
o print (p2.__dict__)

Encapsulation
 Gathering all related methods and attributes in a Class is called
encapsulation
 Here we have created Person class that has related attributes and
methods
 After encapsulation Expert classes are created

Inheritance
 Inheritance is a mechanism where a new class is derived from an
existing class.
 A class may inherit or reuse attributes and methods of other
class.
 A class derived from another class is called a subclass or child
class, whereas the class from which a subclass is derived is
called a superclass or parent class.
Super class
Child class Child class

Inheritance
:Shape
color :String
borderWidth:int
getColor():String
setColor()
getBorderWidth():int
setBorderWidth()
:Rectangle
length :int
width:int
area()
getLength()
setLength()
:Circle
radius : int
area()
getRadius()
setRadius()
:Triangle
base:int
hight:int
area()
getBase()
setBase()
Circle c =new Circle();
c.getColor();
c.getBorderWidth();
c.area();
:object
UML
Notation
4-Jan-20

Why Inheritance ?
 When a class needs to define specialized behavior of a class then
inheritance is required
 For example Circle, Rectangle and Triangle are
providing specialized behavior of Shape class.
 Here Circle, Rectangle and Triangle are called
specialized classes whereas Shape is called generic class
 One class can inherit another class using following syntax:
o class Circle(Shape):
 By default object is root super class of all classes in python

Shape class
 class Shape:
o def __init__(self, c, b):
 self.color = c
 self.borderWidth = b
o def area(self):
 return -1
o def setColor(self, c):
 self.color = c
o def getColor(self):
 return self.color
:Shape
color :String
borderWidth:int
getColor():String
setColor()
getBorderWidth():int
setBorderWidth()

Circle class
 class Circle(Shape):
 PI = 3.14
 #c & b are optional
 def __init__(self, r, c=“”, b=0):
 self.radius = r
 super(Circle,self).__init__(c,b)
 def area(self): #override method
 return self.radius*self.radius*Circle.PI
 Create instance
o c1 = Circle(2,'Red',5)
o c2 = Circle(3,'Blue')
o c3 = Circle(4)
o print(c1.area())

Rectangle Class
 class Rectangle(Shape):
 def __init__(self, length, width , c='', b=0):
 self.length = length
 self.width = width
 super(Rectangle,self).__init__(c,b)

 def area(self):
 return self.length * self.length

Triangle Class
 class Triangle(Shape):
o def __init__(self, base, height , c='', b=0):
 self.base = base
 self.height = height
 super(Rectangle,self).__init__(c,b)
o def area(self):
 return (self.base * self.height) /2

Type of inheritance
1. Single Inheritance
2. Multilevel Inheritance
3. Hierarchical Inheritance
4. Multi Inheritance
A
B
A
B
C
A
B C
A B
C

Multiple Inheritance
 Like C++, a class can be derived from more than one base
classes in Python. This is called multiple inheritance
 class Shape:
o ..
 class Design:
o ..
 class Circle(Shape, Design):
o ..

Method Overriding
 Child classes can override parent class methods
 Circle, Rectangle and Triangle child classes have
overridden area()method of Shape class
 class Shape:
o def area(self):
 return -1
 class Rectangle(Shape):
o def area(self):
 return self.length * self.length

Access Modifier
 Python has three types of access modifiers
o public, private, and protected.
 Public variables can be accessed inside or outside the class
 Private variables can only be accessed inside the class
 Protected variables can be accessed within the same package
 Variable name is prefixed by double underscore (__) to make it private
 Variable name is prefixed by single underscore (_) to make it protected
 Public variables do not have any prefixes
 class Employee:
o def __init__(self):
 self.name = “Ram" #public
 self._code = “E101” #protected
 self.__salary= 25000 #private

Abstract Classes

Abstract class
 Abstract classes are classes that contain one or more abstract
methods
 An abstract method is a method that is declared, but contains no
implementation
 Abstract classes may not be instantiated
 Subclasses are required to provide implementations for the
abstract methods
 For example area() method in Shape class does not have
implementation. Area implementation must be provided by child
classes Circle, Rectangle and Triangle
 Shape will be an abstract class because area()is an abstract
method

Create an abstract class
 Python provides a module to define Abstract Base Classes (ABCs).
 This module is called abc
 You can import abc module using following command:
o from abc import ABC, abstractmethod
 Abstract class is inherited from ABC class and abstract method is annotated by
@abstractmethod annotation
o class Shape(ABC):
o def __init__(self, c, b):
o self.color = c
o self.borderWidth = b
o @abstractmethod
o def area(self):
o pass

Child class
 Child class must implement abstract methods otherwise child will become abstract
 from abc import ABC, abstractmethod
 class Shape(ABC):
 @abstractmethod
 def area(self):
 pass
 class Circle(Shape):
 PI = 3.14
 def area(self):
 return self.radius * self.radius * Circle.PI
 c = Circle(10,"Red",2)
 print(c.area())

Exception Handling
throw
catch
• Exception causes abnormal termination of
program or wrong execution result.
• Python provides an exception handling
mechanism to handle exceptions.
• Exception handling is done by try-except-
else-finally blocks.
• Exception raised in try block is caught by
except block.
• Block finally is optional and always
executed.

Exception Handling
Exception is an error in a program execution that
breaks the normal flow of program.
When you handle these exceptions and execute an
alternate path of program then it is called exception
handling.
Exceptions are handled by following blocks
o try/except
o try/finally

try-except
 a =4
 b = 0
 try:
 c= a/b
 print('C:',c)
 except ZeroDivisionError:
 print("check your dividend is Zero")
 Block except can handle multiple exceptions.
o except ex1,ex2,ex3

Print exception message
 try:
 c= a/b
 print('C:',c)
 except ZeroDivisionError as e:
 print(“Exception:", e)

try-except-else
 a =4
 b = 2
 try:
 c= a/b
 print('C:',c)
 except ZeroDivisionError:
 print("check your division is Zero")
 else: # it will be executed when no exception
 print("Your division was greater than zero")

try-finally
 try:
 c= a/b
 print('C:',c)
 except ZeroDivisionError as e:
 print("Check your division is Zero", e)
 finally:
 print(“Always executed")
 Finally block will be executed whether exception is occurred or
not.

Raise an Exception
 You can raise your custom exception using raise statement
 Raise statement throws instance of Exception class
 try:
 number = int(input("Enter your Number :"))
 if number > 10:
 raise Exception(‘invalid number')
 except Exception as e:
 print(e)

Custom Exception
TODO

Exception List
8
EOFError: Raised when there is no input from either the raw_input() or input()
function and the end of file is reached.
9 ImportError: Raised when an import statement fails.
10 IndexError: Raised when an index is not found in a sequence.
11 KeyError: Raised when the specified key is not found in the dictionary.
12 NameError: Raised when an identifier is not found in the local or global namespace.
13
IOError: Raised when an input/ output operation fails, such as the print statement or
the open() function when trying to open a file that does not exist.
14 RuntimeError: Raised when a generated error does not fall into any category.
15
NotImplementedError: Raised when an abstract method that needs to be implemented
in an inherited class is not actually implemented.

Exception List
# Exception Name & Description
1 Exception :Base class for all exceptions
2
StopIteration :Raised when the next() method of an iterator does not point to
any object.
3 ArithmeticError: Base class for all errors that occur for numeric calculation.
4
OverflowError: Raised when a calculation exceeds maximum limit for a
numeric type.
5 FloatingPointError: Raised when a floating point calculation fails.
6
ZeroDivisionError: Raised when division or modulo by zero takes place for all
numeric types.
7 AttributeError:Raised in case of failure of attribute reference or assignment.

File IO

File IO
 Python provides basic functions to read and write a text and
binary files.
 Function open() is used to open a file into read or write mode.
o file = open(“Hello.txt")
 File can be opened in different mode like read, write, append etc.
o file = open(“Hello.txt“,”w”)
 A file can be closed by its close() method
o file.close()

File Info
 Here is program to read file information
o fo = open("Test.py", “rw”, 0)
o print ("File Name: ", fo.name)
o print ("Mode of Opening: ", fo.mode)
o print ("Is Closed: ", fo.closed)
o fo.close()
 Parameters of open function are:
o Name
o Mode
o Buffering 0: No 1: Yes

Read from File
Here is program that read entire text from file:
o file = open(“Hello.txt") //open a file
o text = file.read() # read all text
o print(text)
o file.close() # close the file
o return
Read binary data
o bArray = file.read(10);

Read Line by Line
You can read file line by line using for loop
o file = open(“Hello.txt")
o for line in file:
o print(line)
o file.close()

Write to a File
Write into a file using write mode
o file = open("Test.txt","w")
o file.write("Hin")
o file.write("This is Python file")
o file.close()

With Statement
 It is used to manage the resources
 It makes code more cleaner
 It automatically closes file when block is finish
 with open("Test.txt","w")as file:
o file.write("Hin")
o file.write("This is Python file")

File Position
 str = fo.read(10);
 position = fo.tell();
 position = fo.seek(0, 0)
 import os
 os.rename( "test1.txt", "test2.txt" )
 os.remove("text2.txt")

Mode of File
Mode Description
r Opens a file for reading only. (It's a default mode.)
w
Opens a file for writing. (If a file doesn't exist already, then it creates a
new file, otherwise, it's truncate a file.)
x
Opens a file for exclusive creation. (Operation fails if a file does not exist
in the location.)
a
Opens a file for appending at the end of the file without truncating it.
(Creates a new file if it does not exist in the location.)
t Opens a file in text mode. (It's a default mode.)
b Opens a file in binary mode.
+ Opens a file for updating (reading and writing.)

Object Serialization
 You may need to store an object into a file or send over the
network that time you need to convert your object into byte
stream, this is called serialization.
 When you restore object from byte stream then it is called
deserialization
Serialization Deserialization
https://pmm.nasa.gov/education/water-cycle

Object Serialization
 The pickle module is used to serialize and de-serialize an object
 Serializing process is called Pickling
 De-serializing process is called Unpickling
 Here we are storing employee object into emp.dat file
 import pickle
 class Employee:
 def __init__(self,eno,ename):
 self.eno=eno
 self.ename=ename
 e = Employee(1,'Mayank')
 f = open('emp.dat','wb')
 pickle.dump(e,f)
 f.close()

Unpickling
import pickle
f = open('emp.dat','wb’)
e = pickle.load(f)
f.close()
print(e.name)

Concurrency and Theading
4-Jan-20
Copyright (c) SunilOS ( RAYS )
Technologies 65

Process
 A process has a self-contained execution environment.
 A process generally has a complete, private set of basic run-time
resources; in particular, each process has its own memory space.
 Python program is executed as a single process.
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Concurrency vs. Parallelism
CPU CPU1 CPU2
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Thread
 Threads are sometimes called lightweight processes.
 Both processes and threads provide an execution environment,
but creating a new thread requires fewer resources than creating
a new process.
 Threads exist within a process
 Every process (application) has at least one thread.
 Threads share resources of their process. Resource are memory
and open files.
 Each thread is associated with an instance of the class Thread
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Threads and Processes
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Multitasking & Multithreading
 Multitasking refers to a computer's ability to perform multiple
jobs concurrently. Multitasking means more than one programs
are running together on a single machine.
 A thread is a single sequence of execution within a program.
 Multithreading refers to multiple threads of control within a
single program. Each program can run multiple threads of
control within it, e.g., Web Browser.
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HelloWithoutThread
 Let’s create two functions hello() and hi(). Run both functions without
thread
 def hello():
 for i in range(15):
 print ( 'Hello ',i)
 def hi():
 print ( 'Hi ‘,i)
 hello()
 hi()
 Both functions will be executed sequentially

HelloWithoutThread output
 Hello 0
 Hello 1
 Hello 2
 …
 Hello 14
 Hi 0
 Hi 1
 Hi 2
 ..
 Hi 14

Hello With Thread
 Let’s create two threads and run hello() and hi()functions inside
thread.
 import threading
 from threading import *
 ..
 t1 = threading.Thread(target = hello)
 t2 = threading.Thread(target = hi)
 #Start threads
 t1.start()
 t2.start()
 Both functions will be executed concurrently

Hello With Thread output
 Hello 0
 Hello 1
 Hello 2
 Hi 0
 Hello 3
 …
 Hi 10
 Hello 14
 Hi 11
 Hi 13
 Hi 14

Thread
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Raktabija
1. Raktabija had a capability to
create another Raktbija by
his single drop of blood.
2. Created Raktabija will be
equally powerful, and can
consume same kind of
resources and work
concurrently.
3. If one Raktabija dies another
will remain active and live.
1. Likewise a Thread can create
another thread.
2. Created Thread will be
equally powerful, and can
consume same kind of
resources and work
concurrently.
3. If one thread dies, other will
remain active in memory.
http://en.wikipedia.org/wiki/Raktavija
4-Jan-20

Creating Threads
 There are two ways to create a Thread
o Create a function and use Thread object to run this function
inside thread
o Inherit Thread class and override run() method
 You need to import threading module to make a thread
o import threading
o from threading import *
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Function as thread
 Create a function and pass its name to target attribute of Thread
constructor
 import threading
 from threading import *
 def hello():
 print ( 'Hello’, i )
 #create thread
 t1 = threading.Thread(target = hello)
 #Start threads
 t1.start()

Parametrized function as thread
 Pass argument array to args attribute of Thread constructor
 def hello(name):
 print ( name , i)
 t3 = threading.Thread(target=hello, args=('Ram',))
 t4 = threading.Thread(target=hello, args=('Shyam',))

Inherit Thread class
 Inherit Thread class and override run() method
 class Hi(Thread):
 def run(self):
 print("Hi", i )
 #Create thread
 t1= Hi()
 #Start thread
 t1.start()

Daemon Threads
 Daemon threads are “background” threads, that provide services
to other threads, e.g., the garbage collection thread
 Program will not exit if non-Daemon threads are executing
 Program will exit if only Daemon threads are executing
 You can make a daemon thread by
 t1 = threading.Thread(target=hello, daemon=True)

Thread Constructor
 class threading.Thread (group=None, target=None,
name=None, args=(), kwargs={}, *, daemon=None)
 group should be None; reserved for future use
 target is the callable function
 args is the argument tuple for the target function
 name of the thread
 kwargs is a dictionary of keyword arguments for the target invocation.
Defaults to {}.
 daemon if given True, it makes thread daemon

Thread handling
 threading.active_count() : returns count of active alive threads
 threading.current_thread(): returns current thread object
 threading.get_ident(): returns id of the current thread
 threading.enumerate(): return a list of all Thread objects
currently alive
 threading.main_thread(): return of main thread that started
Python interpreter
 threading.TIMEOUT_MAX: The maximum value allowed for
the timeout to a blocking function

Synchronization

Synchronization
 Synchronisation is applied on objects or functions, those are
shared by concurrent threads
 Syncronization make sure that a shared resource can be accessed
by only one thread at a time
 Syncronized resources are accessed sequencially by concurrent
threads

Race condition
Syncronization causes race condition among Threads
Threading module provides a Lock class to deal with
the race condition
Following are methods of Lock class:
o lock = threading.Lock(): It creates a lock object
o lock.acquire(): It acquires the lock for current thread
o lock.release(): It releases the lock

Account Class
 Lets create an Account class which will be accessed by concurrent threads
o class Account:
o balance =0
o def get_balance(self):
o sleep(2)
o return self.balance
o def set_balance(self, amount):
o sleep(2)
o self.balance = amount
o def diposite(self, amount):
o bal = self.get_balance()
o self.set_balance(bal + amount)
 It is assumed that set and get balance operation takes 2 seconds to execute

Racing Thread
 class Racing(Thread):
 account: Account
 name = ""
 def __init__(self,account, name):
 super().__init__()
 self.account = account
 self.name = name
 def run(self):
 self.account.diposite(100)
 print( self.name, self.account.get_balance())
 t1 = Racing(acc, "Ram")
 t2 = Racing(acc, "Shyam")
 t1.start()
 t2.start()
• Racing thread is depositing
Rs 1000 five times in the
account
• Two threads are started and
both are racing to deposit
amount

Output
 Shyam 100
 Ram 100
 Shyam 200
 Ram 200
 Ram 300
 Shyam 300
 Ram 400
 Shyam 400
 Shyam 500
 Ram 500

Synchronize deposit
 class Account:
 balance =0
 def __init__(self):
 self.lock = threading.Lock()
 def get_balance(self):
 sleep(2)
 return self.balance
 def set_balance(self, amount):
 sleep(2)
 self.balance = amount

 def diposite(self, amount):
 self.lock.acquire()
 bal = self.get_balance()
 self.set_balance(bal + amount)
 self.lock.release()

Output
 Ram 100
 Shyam 200
 Ram 300
 Shyam 400
 Ram 500
 Shyam 600
 Ram 700
 Shyam 800
 Ram 900
 Shyam 1000

 Emails are sent by SMTP protocol
 Module smtplib is used to send an email
 You can send plain text or HTML text in email body
 You can attach files with emails
 Following SMTP servers can be used to send an email
o GMail
o Yahoo
o Hotmail
o Etc.
Email

Send Plain Text in Email
 import smtplib
 smtp_server = "smtp.gmail.com"
 port = 587 # For TLS
 sender_email = "webmaster@sunrays.co.in"
 password = input("Enter password and press enter: ")
 receiver_email = “myfriend@gmail.com"
 message = """From: Sunil Sahu <webmaster@nenosystems.com>
 CC: sunil.sahu@nenosystems.com
 Subject : Hi from python

<H1>HI this is my first email from Python.</H1>
 """
 smtp = smtplib.SMTP(smtp_server,port)
 smtp.starttls() #Enable transport layer security
 smtp.login(sender_email,password)
 smtp.sendmail(sender_email, receiver_email, message)
 smtp.quit()

Secure Email
 An SMTP connection is secured and encrypted so that message and login credentials
are not easily accessed by others
 SSL (Secure Sockets Layer) and TLS (Transport Layer Security) are two protocols
that can be used to encrypt an SMTP connection.
 Gmail SMTP server provides 465 port for SSL and 587 port for TLS connection
 There are two ways to secure connection
 Making SSL connection
 connection = smtplib.SMTP_SSL(smtp_server, 465)
 connection.login(sender_email,password)
 Enable TLS by calling method smtplib.starttls()
 connection = smtplib.SMTP(smtp_server, 587)
 connection.starttls()
 connection.login(sender_email,password)

Email Subject & Body
 Email contains subject and body text message
 Subject and body text are delimited by two new line characters
(nn) and prefixed by “Subject : ” word
o subject = "First Email"
o text = "How are you ?"
o body = "Subject: " + subject + " nn " + text
o connection.sendmail(sender_email, receiver_email, body)

HTML content
 Python provides MIME (Multipurpose Internet Mail Extensions) Multipart
emails.
 Mutiple part email contains mutiple parts in email like plain text, html text,
files etc.
 It is used to send HTML emails and file attachements
 Module email.mime provides classes to make mutiple part emails.
o import smtplib
o from email.mime.multipart import MIMEMultipart
o from email.mime.text import MIMEText
o from email.mime.base import MIMEBase
o from email import encoders

Send HTML Email
 text = “Hi How are you”
 html = "<html><body><h1>Hi, How are you</h1></body></html>

 msg = MIMEMultipart() # instance of MIMEMultipart
 msg['From'] = sender_email # storing the senders email address
 msg['To'] = receiver_email # storing the receivers email address
 msg['Subject'] = "This is Mutipart email" # storing the subject
 msg.attach(MIMEText(text, 'plain')) #plain text part
 msg.attach(MIMEText(html, 'html')) #html text part

 s = smtplib.SMTP('smtp.gmail.com', 587)
 s.starttls()
 s.login(sender_email, password)
 s.sendmail(sender_email, receiver_email, msg.as_string())
 s.quit()

Attach A File
 In multipart email you can also attach one or more files as a part.
 filename = "SimpleMail.py"
 with open(filename, "rb") as attachment:
 # instance of MIME Base and named as p
 p = MIMEBase('application', 'octet-stream')
 # To change the payload into encoded form
 p.set_payload((attachment).read())
 # encode into base64
 encoders.encode_base64(p)
 p.add_header('Content-Disposition’ , "attachment;
filename= %s" % filename)
 # attach the instance 'p' to instance 'msg'
 msg.attach(p)

Tkinter

Networking

Database Connectivity

DJango

References
 https://docs.python.org/3/library/threading.html
 https://realpython.com/python-send-email/
 https://likegeeks.com/python-gui-examples-tkinter-tutorial/

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