This document discusses design patterns in Python. It provides a brief history of design patterns, beginning with Christopher Alexander's work in architecture. It then discusses the Gang of Four's influential book on design patterns from 1994. As an example, it covers the Proxy pattern, explaining how it can solve the problem of long loading times for high-resolution images on a website by using placeholders. It also demonstrates the Adapter and Observer patterns. While some criticize that design patterns can be replaced with built-in functionality or are more relevant to languages like Java, the document argues they help create well-structured, abstract software in less time and provide a shared language. It encourages looking at patterns when needed and lists references for further information.

1. @PJUllrich - peterullrich.com
DESIGN PATTERNS IN PYTHON
BY PETER ULLRICH

2. RAW CODE

3. SOFTWARE DESIGN

4. SOFTWARE ARCHITECTURE

5. A SHORT
HISTORY
OF
SOFTWARE DESIGN

6. Christopher Alexander (Real-world Architect) 253 - 1977
Image attribution: wikipedia.org

7. 1994
GANG OF FOUR
Image attribution: wikipedia.org

8. 23 Image attribution: wikipedia.org

9. WHAT IS A
DESIGN PATTERN

10. EXAMPLE DESIGN PATTERN
PROXY PATTERN
▸ Problem
▸ high-res images on website
▸ Long loading time
▸ Style images
▸ Solution
▸ Replace with placeholders
(proxies)
▸ Style placeholders instead

11. EXAMPLE DESIGN PATTERN
PROXY PATTERN
▸ Problem
▸ high-res images on website
▸ Long loading time
▸ Style images
▸ Solution
▸ Replace with placeholders
(proxies)
▸ Style placeholders instead

12. HOW TO USE
DESIGN PATTERNS
A SHORT STORY
Created with Storyboard That

36. ADAPTER
DESIGN PATTERN

38. DEMO

42. FACADE
DESIGN PATTERN

44. DEMO

46. OBSERVER
DESIGN PATTERN

48. DEMO

50. CRITICISM

51. DESIGN PATTERNS CAN BE
REPLACED WITH BUILT-IN
FUNCTIONALITY
John Doe
CRITICISM

52. CRITICISM
DESIGN PATTERNS CAN BE REPLACED WITH BUILT-IN FUNCTIONALITY
▸ Yes and No
▸ Some design patterns Yes
▸ Iterator
▸ Many Not
▸ Facade, Adapter, …

53. DESIGN PATTERNS ARE MORE
FOR JAVA OR C#, NOT PYTHON
Jane Doe
CRITICISM

54. CRITICISM
DESIGN PATTERNS ARE MORE FOR JAVA OR C#
▸ No
▸ Certainly more prevalent in such fields
▸ But also important in Python
▸ Help get a more abstract understanding of software
▸ Help create well structured software in less time
▸ Offer a shared language to communicate

55. TAKE AWAYS

56. TAKE AWAYS
▸ Have a look at Design Patterns
▸ Study them, Forget them, Look them up when needed
▸ You will write better software
▸ More helpful (and necessary) the more senior you
become

57. THANK YOU

58. ▸ https://sourcemaking.com/design_patterns
▸ http://python-3-patterns-idioms-test.readthedocs.io/en/
latest/PatternConcept.html
▸ https://github.com/faif/python-patterns
REFERENCES