Design Pattern in Python with 100+ Real World Code Examples

Explore the builder design pattern, a creational approach that constructs complex objects step by step using the same construction code and separates construction from representation to handle many optional parameters.

Explore real world uses of the builder design pattern across domains like document creation (pdf, html), GUI development, meal orders, car configurations, web pages, game levels, and SQL queries.

Explore essential builder pattern terminology, including product, builder, concrete builder, director, and client, and understand how each role contributes to constructing complex objects.

Discover how the builder pattern decouples construction from representation by building houses with a builder, chaining floor, wall, and roof settings, and printing the final results.

Explore the builder design pattern in Python by constructing small and big houses with concrete builders guided by a director that orchestrates floor, wall, roof, and furniture assembly.

See how to implement the builder design pattern in Python through a real-world sandwich builder example, creating sandwiches with optional ingredients.

Apply the builder design pattern to assemble a game object with transformer, renderer, collider, and script. Build the game step by step using the game builder.

Build a SQL query builder in Python using the builder design pattern to incrementally assemble select, from, where, group by, order by, and limit clauses, producing the final query string.

Use the builder pattern to isolate construction code from the rest of the codebase while creating complex objects with multiple parts and representations, enabling fluent chaining and modular design.

Explore the builder design pattern's advantages, including decoupling abstraction from implementation, improved extensibility, fewer subclasses, and runtime switchability, alongside disadvantages like added complexity, performance overhead, and testing challenges.

Learn how to use the builder design pattern in Python, including object literals, keyword arguments, and data classes, with optional defaults and fluent interfaces to reduce boilerplate.

Explore the factory method design pattern, a creational pattern that provides an interface for creating objects while subclasses decide which class to instantiate, enabling loose coupling and open/closed behavior.

Explore how the factory method pattern drives real world use cases across document processing, logging, database connectivity, gui components, serialization, payment gateways, maze generation, vehicle manufacturing, plugins, and game objects.

Explore core terminologies of the factory method design pattern in Python, including product, concrete product, creator, concrete creator, factory method, and client.

Explore the factory method design pattern in python with concrete products like car and bicycle, using abstract bases, creators, and concrete factories to generate and operate products.

Refactor a vehicle system using the factory method design pattern with a vehicle factory and abstract vehicle start method, creating car, motorcycle, and bicycle instances.

Master the factory method pattern by building a skeletal document processing app that creates word, pdf, and html documents and opens them through a unified interface.

Implement a login framework using the factory method design pattern to create console, file, and database loggers with an abstract logger and concrete implementations.

Explore the differences between the factory method and factory design pattern through a database connectivity example, creating MySQL, Postgres, and Oracle connections and comparing flexibility, simplicity, and testability.

Use the factory method design pattern to encapsulate object creation and decouple client code from concrete classes. Extend and test objects easily with specialized factory classes.

Examine the advantages and disadvantages of the factory method design pattern, including encapsulation, modularity, testing, and reusability, alongside increased complexity and indirection.

Define an abstraction for products, implement concrete classes, and encapsulate creation in a static factory method; enable client code to interact via the factory method and support extensibility.

Explore the abstract factory design pattern, a creational approach that creates families of related objects via an interface and separates creation from implementation.

Explore real world uses of the abstract factory pattern across GUI toolkits, game engines, databases, and document generators to create appropriate objects per context.

Explore terminologies used in the abstract factory pattern, including abstract factory, concrete factory, abstract product, concrete product, product family, factory hierarchy, and client.

Explore the abstract factory design pattern by building small and big houses, each filled with furniture, electronics, and decorations; see how a house factory creates and displays related amenities.

Explore a real-world database connectivity example built with the abstract factory design pattern. Create MySQL and Postgres connections and cursors, then connect and execute queries via the factory-created products.

Explore the abstract factory design pattern by building a country-specific payment gateway offering credit card, debit card, net banking, and remitter options, with PayPal and new countries easily added.

Implement a game engine using the abstract factory design pattern to create character, weapon, and level families for medieval, modern, and sci-fi games, each with a display abstract method.

Compare factory method and abstract factory patterns by explaining how each creates objects, defines interfaces, and lets subclasses or factories choose concrete classes or families of related objects.

Explore how the abstract factory design pattern promotes loose coupling, enables product family creation, and provides a consistent interface for exchanging implementations.

Define abstract interfaces with ABC, implement concrete products and factories, and use dependency injection so the client relies on abstractions; enforce Liskov substitution principle, naming conventions, and unit tests.

Explore the object pool design pattern, a creational design pattern that reuses objects via a pool manager to boost performance and reduce creation overhead.

Explore real world uses of the object pool design pattern across databases, thread pools, graphics, and web servers. The lecture highlights resource reuse in I/O, messaging, ORM, and distributed systems.

Define the core terminologies of the object pool design pattern, including pool manager, object pool, available and in-use objects, and steps such as object creation, allocation, deallocation, and reset reinitialization.

Explore the object pool design pattern by implementing an object pool manager that initializes a set of objects, tracks available and in-use objects, and handles acquisition, release, and reset.

Implement a connection pool using the object pool design pattern in Python, with a connection object and a pool manager to acquire and release available connections.

Demonstrates a Python object pool for database connections with sqlite3, a connection class, acquire and release methods, and an employee table initialized for concurrent queries and inserts.

Demonstrates a connection pool in a messaging system using the object pool pattern, with a queue, threading, and a lock to manage acquire and release of connections.

Use the object pool design pattern to reuse pre-initialized resources like database, network, and thread connections, reducing initialization overhead and improving performance under limited or fluctuating demand.

Explore the advantages and disadvantages of the object pool design pattern, highlighting performance gains, resource optimization, thread safety, and scalability, alongside complexity, overhead, stale state, and memory considerations.

Implement a thread-safe object pool design by enforcing synchronization, cleaning and reinitializing objects, and tuning pool size, lifecycle, and performance to prevent leaks and stale state.

Explore how the singleton design pattern ensures a class has a single instance and provides a global access point via a private constructor, static instance, and static method.

Explore real world use cases of the singleton design pattern, including database connections, configuration settings, and an event manager, emphasizing a single instance across the application.

Explore singleton terminology in Python, including the singleton class, the instance, and the get instance method. Learn about lazy initialization, a private init, and thread safety for multi-threaded access.

Explore the singleton design pattern by contrasting a non singleton class with a single shared instance, using a get_instance method to ensure only one object exists and minimizes memory usage.

Implement a file-based logger using the singleton design pattern, with info, warning, error, and critical levels, ensuring all logs write to the first instance file (file one.txt) via get_instance.

Demonstrate converting a non-singleton database connection to a singleton in Python with MySQL connector. Use a class with a get_connection method to ensure one shared connection and save memory.

Explore key notes when implementing the singleton pattern in Python, including multi-threaded concerns and dynamic class behaviors. Understand how singletons enable sharing across codebase and control access to global state.

Explore the prototype design pattern, a creational technique that creates new objects by copying existing ones instead of from scratch, and use prototypes to clone as needed.

Explore real world uses of the prototype design pattern to clone and modify graphics objects, templates, and configurations across design tools, code editors, game engines, 3D modeling, and virtual machines.

Explore terminologies in the prototype design pattern, including the prototype interface, concrete prototype, clone method (shallow and deep copies), client-specific modifications, and the prototype registry.

Build a prototype design pattern by storing objects in a dictionary within a prototype engine, register and unregister them, then clone via deep copies.

Apply the prototype design pattern to create web pages by cloning a shared template with header, footer, and configurable content.

Demonstrates a document management system using the prototype pattern to clone template documents (contracts, reports, presentations) via deep copies, with a prototype engine, register/unregister, and a clone operation.

Implement a product templating system for e-commerce using the prototype design pattern, cloning prototypes to create new clothing and electronics products.

Register prototypes in a game engine and clone them using the prototype design pattern, customizing health and strength for characters and enemies with deep copy.

Explore the prototype design pattern, using cloning to create similar objects efficiently, while weighing advantages like cost reduction and encapsulation against drawbacks such as complexity and shallow versus deep copying.

Analyze key notes for the prototype design pattern in Python, including shallow vs deep copies, cloning costs, thread safety, organized prototype registries, and defensive copying to protect object identities.

Explore adaptive design pattern, a pattern that enables incompatible interfaces to work together via an adapter object that translates interfaces for client, wrapping existing code without modifying the original class.

Examine how the adapter design pattern translates interfaces across devices, including power adapters, USB to serial ports, audio adapters, database adapters, language translators, and printer adapters.

Explore terminologies used for adaptive design patterns, including target, adaptive, adapter, and client, and explain how the adapter implements the target interface and works with the adaptive.

Apply the adapter pattern to convert an external model with a complex request method into the code base’s standard request method via a target contract and adapter class.

Explore the object and class adapter patterns in Python, using composition or multiple inheritance to adapt existing classes to a new interface via a unified request method.

Learn how to implement an audio adapter that bridges an advanced audio player to a legacy media player, enabling mp3, wav, and mp4 playback through a unified play method.

Explore how to implement a database adapter using the adapter pattern to unify insert, delete, update, and select methods across MySQL and Postgres with a shared interface.

Illustrates building a language translator with the adapter pattern by unifying Google Translate and Yandex Translate APIs under a single translator interface.

Use the adapter pattern to reuse existing code with a different interface by wrapping it in a compatible, simpler interface that handles multiple or future classes without modifying the original.

Explore the adapter design pattern's advantages—flexibility, reusability, maintainability, scalability, and simplification—along with disadvantages like performance, maintenance, and dependency inversion.

Explore adapter design patterns in Python, comparing object adapters and class adapters, with object adapters using composition and class adapters via inheritance. Define interfaces or abstract classes, test thoroughly.

Explore the bridge design pattern in object-oriented design, decoupling abstraction from implementation with two hierarchies and a bridge object to enable flexible, maintainable code.

Explore real-world uses of the bridge pattern to decouple abstraction from implementation across domains like graphic design, streaming interfaces, operating systems, databases, remote controls, web frameworks, robotics, and game development.

Explore bridge design pattern terminologies: abstraction, refined abstraction, implementation, and concrete implementation, with a bridge decoupling abstraction from implementation and a client accessing the abstraction to apply color choices.

Illustrate the bridge design pattern by separating shape abstractions from color implementations, using abstract base classes and a dunder string method to create red, blue, and green circles, squares, rectangles.

Apply the bridge design pattern to a music player that integrates Spotify and Apple Music with other implementations by creating a music player abstraction and a play song method.

Demonstrate a platform independent file app using the bridge pattern to perform open, close, and rename operations via Windows, Linux, and Mac OS implementations.

Build a real-world web application framework with the bridge design pattern, decoupling the web application abstraction from database drivers like MySQL and Postgres, enabling route, render, and execute query.

Apply the bridge pattern to decouple an abstraction from its implementations, enabling runtime switching and dynamic addition or removal of implementations while hiding details for a simpler interface.

Explore the bridge design pattern, showing how decoupling abstraction and implementation enables independent variation, extensibility, flexibility, and reuse, while acknowledging added complexity, development time, and potential performance overhead.

Implement the bridge pattern in Python by leveraging dynamic typing and duck typing, defining clear abstraction and implementation, using composition over inheritance, and managing resources with the with statement.

Explore the composite design pattern as a structural design pattern that treats leaves and composites uniformly, enabling operations on a hierarchical tree as a single object or on individual components.

Explore real world use cases of the composite design pattern across file systems, organizational charts, gui components, music playlists, html documents, manual menus, and computer networks, emphasizing hierarchical structures.

Explore the terminologies of the composite design pattern, including the common interface, leaf and composite objects, client interactions, and recursive composition forming a tree-like structure.

Learn to implement a composite pattern with a component and composite classes that can add or remove children and perform operations uniformly.

Build a hierarchical menu system with the composite pattern, featuring menus and leaf items, where the menu class adds, removes, and prints the structure via LHS.

Create a restaurant menu system using an abstract menu component and composite to add, remove, and display nested menus with items showing names and prices or descriptions.

Create an organizational chart using the composite pattern to model departments and employees, compute total salaries, and print a hierarchical, indented chart.

Use the composite design pattern to model hierarchical objects, treating individuals and groups uniformly with a common interface in a tree-like structure that supports runtime add or remove operations.

Explore how the composite pattern simplifies code with a uniform interface and encapsulation for hierarchical structures, enabling extensibility, while incurring potential performance overhead and limited type hierarchy.

Define a common interface for all components to ensure uniform handling. Implement the composite and leaf objects, use recursion to traverse hierarchies, and address type safety and performance with optimizations.