python - A basic notes for beginners(newbies)

python - A basic notes for beginners(newbies)

• 1.
  PYTHON / DJANGO
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  PYTHON • High level •Interpreted Language • Object oriented • Dynamically typed • Multi-Paradigm • Open Source and Free • Scalable and Extensible
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  High Level • Pythonis close to human language, • not machine language. • don’t have to manage memory or hardware details. • Example print(“helllllo Universeee”)
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  Interpreted Language • Pythoncode is executed line by line. • No need to compile before running. • Errors are shown immediately. • Code → Interpreter → Output
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  Object-Oriented • Python supportsclasses and objects • Helps organize large programs into reusable components. • Follows OOP concepts: • Encapsulation • Inheritance • Polymorphism • Abstraction • Example class Student: def __init__(self, name): self.name = name
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  Dynamically Typed • Noneed to declare variable types. • DataType is decided at runtime. • Example x = 10 # integer x = "AI" # string
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  Multi-Paradigm Python supports multipleprogramming styles: • Procedural print("Hello") • Object-Oriented class Car: pass • Functional numbers = [1, 2, 3] result = list(map(lambda x: x*2, numbers))
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  Open Source andFree • Python is free to use, modify, and distribute. • Source code is publicly available. • Supported by a large global community. • No license cost for individuals or companies.
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  Scalable • Can growwith project size. • Used by companies like Google, Netflix, and Instagram. • Python works for: • Small scripts • Medium applications • Large enterprise systems
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  Extensible • Python canintegrate with: • C / C++ • Java • Databases • APIs • Performance-critical parts can be written in faster languages.
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  Important terms toknow • Function - A function is a reusable block of code that performs a specific task. • Module - A module is a single Python file (.py) that contains functions, variables, or classes. • Library - A library is a collection of modules that provide related functionality. • Package - A package is a collection of modules organized in folders.
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  • Class -A class is a blueprint for creating objects. It defines variables and methods. • Object - An object is a real instance of a class. It represents real-world entities and contains data (variables) and behavior (methods). • Keyword - they are reserved words with predefined meaning in Python. • Indentation - defines code blocks instead of { }. • Namespace - is a container that holds variable names and their values. • Scope - defines where a variable can be accessed. • Generator - produces values one at a time using yield.
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  DJANGO • Django isa high-level Python web framework used to build secure, scalable, and maintainable web applications quickly. • Django helps you build backend web applications without reinventing the wheel.
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  WHY DJANGO • Fastdevelopment – lots of built-in features • Secure by default – protects against common attacks • Follows best practices – clean, organized code • Batteries included – admin panel, ORM, auth, forms • Used by big companies (Instagram, Pinterest, Mozilla)
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  M V TDESIGN PATTERN • Model - The data you want to present, usually data from a database. • View - A request handler that returns the relevant template and content - based on the request from the user • Template - A text file (like an HTML file) containing the layout of the web page, with logic on how to display the data.
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  Component Role EasyMeaning Model Database logic Tables & data View Business logic Brain of app Template UI HTML pages
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  • Django receivesthe URL, checks the urls.py file, and calls the view that matches the URL. • The view, located in views.py, checks for relevant models. • The models are imported from the models.py file. • The view then sends the data to a specified template in the template folder. • The template contains HTML and Django tags, and with the data it returns finished HTML content back to the browser.