Dummy Library Project

• We are supposed to develop the Library in Python

• This project will be used by librarian, faculty, students

• As of now Library has

  • Books
  • Magazines
  • DVD’s
  • E-books

• You have to implement the functionality to support the whole library activities

• To implement this kind of project we might need to deal with lot of objects.

• We would be defining/writing the code in multiple py files

• So how should i organize the multiple py files

• Modules are simply python files. so each python file is a module

• So to develop the library application i will end up creating multiple modules

Lets look at multi module demo

• Lets create a new folder moduledemo and in that create two python files app.py and database.py
• Each file is a module. so in database.py add the following code

class Database:
    def __init__(self):
        pass

    def connect(self):
        pass

    def disconnect(self):
        pass

• Now in app.py i want to create a database connection, so we need to create a object and then call method.
• To use Class Database in app.py we need to import modules. Importing modules in python can be done by import statement
• Using import statement i can import module or specific classes or functions from module.
• Importing complete module

import database

db = database.Database()
db.connect()

• importing specific class

from database import Database

db = Database()
db.connect()
db.disconnect()

• Now lets create one more module called as utils.py

class DbUtils:
    pass

class FileUtils:
    pass

class HttpUtils:
    pass

• Now lets assume if app.py module wants FileUtils and HttpUtils

from utils import FileUtils, HttpUtils

# instantiating Objects of FileUtils
file_utils = FileUtils()

# instantiating Objects of HttpUtils
http_utils = HttpUtils()

• Some sources say that we will be importing all the classes and functions from the module using this syntax (Don’t do this)

from utils import *

• As number of modules grow it would be logical to organize modules in some folders based on usage
• A package is a collection of modules in a folder. The name of the package is name of folder
• Lets create three packages called as
  • common
  • utilities
  • models
• The package will be shown in pycharm as
• We need to tell python that folder is a package to distinguish it from other folders. To do this we would be a file in the folder __init__.py
• This file can be empty. If we forget this file, we wont be able to import modules from that folder.
• So now lets create some modules in package common
• Absolute imports specify the complete path to the module, function or class we want to import
• Refer to todays class at the following location
  • Refer Here for dummy library
  • Refer Here for module demo