Book Image

Python: Master the Art of Design Patterns

Book Image

Python: Master the Art of Design Patterns

Overview of this book

Python is an object-oriented scripting language that is used in everything from data science to web development. Known for its simplicity, Python increases productivity and minimizes development time. Through applying essential software engineering design patterns to Python, Python code becomes even more efficient and reusable from project to project. This learning path takes you through every traditional and advanced design pattern best applied to Python code, building your skills in writing exceptional Python. Divided into three distinct modules, you’ll go from foundational to advanced concepts by following a series of practical tutorials. Start with the bedrock of Python programming – the object-oriented paradigm. Rethink the way you work with Python as you work through the Python data structures and object-oriented techniques essential to modern Python programming. Build your confidence as you learn Python syntax, and how to use OOP principles with Python tools such as Django and Kivy. In the second module, run through the most common and most useful design patterns from a Python perspective. Progress through Singleton patterns, Factory patterns, Façade patterns and more all with detailed hands-on guidance. Enhance your professional abilities in in software architecture, design, and development. In the final module, run through the more complex and less common design patterns, discovering how to apply them to Python coding with the help of real-world examples. Get to grips with the best practices of writing Python, as well as creating systems architecture and troubleshooting issues. This Learning Path combines some of the best that Packt has to offer in one complete, curated package. It includes content from the following Packt products: ? Python 3 Object-Oriented Programming - Second Edition by Dusty Phillips ? Learning Python Design Patterns - Second Edition by Chetan Giridhar ? Mastering Python Design Patterns by Sakis Kasampalis
Table of Contents (6 chapters)
4
A. Bibliography
5
Index

Chapter 9. The Proxy Pattern

In some applications, we want to execute one or more important action before accessing an object. An example is accessing sensitive information. Before allowing any user to access sensitive information, we want to make sure that the user has sufficient privileges. A similar situation exists in operating systems. A user is required to have administrative privileges to install new programs system-wide.

The important action is not necessarily related to security issues. Lazy initialization [j.mp/wikilazy] is another case; we want to delay the creation of a computationally expensive object until the first time the user actually needs to use it.

Such actions are typically performed using the Proxy design pattern. The pattern gets its name from the proxy (also known as surrogate) object used to perform an important action before accessing the actual object. There are four different well-known proxy types [GOF95, page 234], [j.mp/proxypat]. They are as follows...