DESIGN PATTERNS WITH PYTHON

how to apply design patterns to create python programs that easy to write, read and maintain.

Transcript

1. DESIGN PATTERNS WITH PYTHON Cleopatra Douglas @succedor23
2. Objective-oriented design principles Design Patterns Programming challenges Business problems Several IDEs MAJOR TOPICS
3. Expectations At the end of this course you would have learnt how to apply design patterns to create python programs that easy to write, read and maintain.
4. WHAT ARE DESIGN PATTERNS? WHY DO WE NEED THEM? CLASSIFICATION PRINCIPLES OF OBJECT-ORIENTED DESIGN SOLID DEFINING INTERFACES IN PYTHON OVERVIEW 1
5. WHAT ARE DESIGN PATTERNS? A design pattern is a model solution to a common design problem. It describes the problem and a general approach to solving it.
6. ‘Each pattern describes a problem which occurs over and over again in our environment and then describes the core of the solution to the problem’ - Christopher Alexander (An Architect)
7. Building architecture Automobile Design Electrical and plumbing codes Mobile phones interfaces EXAMPLES OF EVERYDAY DESIGN PATTERNS
8. WHY DO WE NEED DESIGN PATTERNS? We need to design patterns to ensure that our work is consistent, reliable and understandable.
9. CLASSIFICATION CREATIONAL Object Creation STRUCTURAL Object relationships BEHAVIORAL Object interaction and responsibility.
10. S - SINGLE RESPONSIBILITY O- OPEN-CLOSED L- LISKOV SUBSTITUTION I- INTERFACE SEGREGATION D- DEPENDENCY INVERSION
11. WHAT PYTHON VERSION We will be referencing python language 2.7x or 3.5x -https://www.python.org/downl oads/
12. INTERFACES IN PYTHON THIS IS ‘ I ‘ IN SOLID Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Incididunt ut labore et dolore. Consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
13. STRATEGY PATTERN CLASSIFICATION: BEHAVIORAL FAMILY OF ALGORITHMS ENCAPSULATE EACH ONE MAKE THEM INTERCHANGEABLE ALSO KNOWN AS POLICY PATTERN
14. EXAMPLE ONLINE SHOPPING WEBSITE SHIPPING PAGE Must Support: - FEDEX - UPS - Nigerian Postal Service Must be extendable (add new shippers)
19. Violates Single Responsibility Principle Violates Open/Closed Principle Violates Dependency Inversion Principle Long list of if/elif clauses
24. Fixed the problems we discovered Test of algorithms in isolation Test the outer code with deterministic mock algorithms No more Long list of if/elif clauses
25. Strategies as functions Strategies as lambas VARIATIONS
26. SUMMARY OF STRATEGY PATTERN Encapsulated algorithms Several techniques avaliable Sequence of if/elif are a red flag
27. OBSERVER PATTERN CLASSIFICATION: BEHAVIORAL ONE TO MANY RELATIONSHIP BETWEEN A SET OF OBJECTS WHEN THE STATE OF ONE CHANGES ITS DEPENDENTS ARE NOTIFIED ALSO KNOWN AS: DEPENDENTS PATTERN PUBLISH-SUSCRIBE PATTERN
28. EXAMPLE DASHBOARD FOR A TECH SUPPORT CENTER KPIs: - Open Tickets - New tickets in last hour - Closed tickets in last hours Dashboard is the observer KPI source is the subject or publisher.
35. Used in command lines and GUI’s COMMAND PATTERN
37. Singleton pattern Factory pattern Builder pattern Other patterns
38. THANK YOU