Object-Oriented Programming, Design with TDD in Pharo

About this course

This lecture will teach you the way program with live objects. We use Test Driven Development and show Object-Oriented Design using multiple examples.

Object-oriented programming is more than just writing algorithms. It is identifying objects, defining the behavior of such objects and how they collaborate together. Object-oriented design experts think in terms of responsibilities and collaborations that an object has. In addition finding a good design is a challenging task that depends on the context and often there is no such thing that the perfect correct solution. There are tradeoffs. Therefore good design is often the result of an iterative process. In this course we will follow the expression: "Designing starts when the program compiles" it means that we will first get a first version and think about it and since we will have written tests we will be able to change the design and improve it. This way you will learn by doing.

In this lecture we will focus on object-oriented programming concepts:

• Objects / Classes
• Messages / Methods
• self/this and its semantics
• Inheritance
• super and its semantics
• Tests are your life ensurance

• Class responsibility collaboration
• Delegation
• Message sends are choice (what would be the equivalent to not)
• Message sends are plans for reuse
• Polymorphism
• The "Don't ask, tell" Principle
• Some design patterns

We decided to use Pharo. Pharo is not mainstream but it is used in many Universities in the world to teach object-oriented programming because it is one of the best language to grasp the complex design forces that makes good design. Pharo syntax is small and Pharo model is pure and elegant. What you will learn can be applied to any object-oriented programming language. more…

Resources

• Join the Discord mooc channel of the Pharo community (Invitation at http://discord.gg/Sj2rhxn)
• Pharo Mooc http://mooc.pharo.org and the Mooc Videos. You can also use the Mooc Portal (packaged videos with subtitles).
• Pharo By Example (50) http://books.pharo.org
• A book: Learning Object-Oriented Programming and Design with TDD in Pharo (PDF)
• Pharo Cheat Sheet

Exercises

• Do the ProfStef tutorial by executing ProfStef go in a playground
• Counter
• Katas
• DSL
• (optional) ElectronicWallet
• (optional) Snake and Ladder

Week 1: Welcome on Board and Syntax Discovery

1. [Lecture] W1S00-Intro-Objectives
2. [Lecture] W1S01-What is Pharo?
3. [Lecture] W1S02-Pharo Vision
4. [Lecture] W1S03-FirstLookAtClassObjectMethods
5. [Lecture] W1S04-PharoModelInaNushell
6. [Lecture] W1S04-TestIntroduction
7. [Lecture] W1S05-PharoSyntaxInANutshell
8. [Lecture] W1S06-Blocks
9. [Lecture] W1S07-Basic-Blocks-Loops
10. [Lecture] W1S07-BasicBooleansAndCondition
11. [Lecture] W1S08-Loops
12. [Lecture] W1S10-ClassAndMethodDefinition
13. [Live Exercise] Selecting and executing expressions (check the subtitles here )
14. [Live Exercise] Syntax Highlighting gives Feedback (check the subtitles here )
15. [Live Exercise] Learn Keyboard Shortcuts (check the subtitles here )
16. [Live Exercise] Learn Pharo with Prof Stef (check the subtitles here)
17. [Exercise] Expressions and Messages
18. [Live Exercise] Coding a Counter (check the subtitles here)

You can access

1. the Week session slides
2. the Pharo Mooc videos. Pay attention they may be not in the same order - Check the Resources slide in the lectures to get the corresponding Pharo Mooc session.

Week 2: Pharo Syntax and Inspector

1. [Lecture] W2S01-Messages
2. [Lecture] W2S02-Messages-ForTheJavaProgrammers
3. [Lecture] W2S03-Basic-Variables
4. [Lecture] W2S03-Messages-Precedence
5. [Lecture] W2S04-Messages-Sequence
6. [Lecture] W2S05-ParenthesisVsSquareBrackets
7. [Lecture] W2S06-Yourself
8. [Lecture] W2S07-CharacterStringSymbol
9. [Lecture] W2S08-Basic-ArraySetOrderedCollection
10. [Lecture] W2S09-UnderstandingMistakes
11. [Lecture] W2S10-Iterators
12. [Lecture] W2S11-Streams
13. [Lecture] W2S12-RuntimeArchitecture
14. [Live Exercise] GTInspector 1: Inspect and Interact with Objects (check the subtitles here)
15. [Live Exercise] Spotter 1: Find and Browse a Class (check the subtitles here)
16. [Challenge] Challenge 0

You can access

1. the Week session slides
2. the Pharo Mooc videos. Pay attention they may be not in the same order - Check the Resources slide in the lectures to get the corresponding Pharo Mooc session.

Week 3: Objects, Classes, Methods

1. [Lecture] W3S00-TeapotAsAPretext
2. [Lecture] W3S01-WhatisAnObject
3. [Lecture] W3S02-WhatisAClass
4. [Lecture] W3S03-MethodVsMessages
5. [Lecture] W3S04-OOParadigm
6. [Lecture] W3S05-SUnit
7. [Lecture] W3S06-Discovering
8. [Lecture] W3S7-EssenceOfDispatchExo
9. [Live Exercise] Nautilus: First Meet with the Code Browser (check the subtitles here)
10. [Live Exercise] Nautilus: Packages, Tags and Groups (check the subtitles here)
11. [Live Exercise] Nautilus: How to Become a Super Pharo Developer: Understanding Sender and Implementors (check the subtitles here)
12. [Live Exercise] Finding Methods with Finder (check the subtitles here)
13. [Live Exercise] Coding a Counter in the Debugger (check the subtitles here)
14. [Exercise] Coding a DSL
15. [Challenge] Challenge 1

You can access

1. the Week session slides
2. the Pharo Mooc videos. Pay attention they may be not in the same order - Check the Resources slide in the lectures to get the corresponding Pharo Mooc session.

Week 4: Essence Of OOP

1. [Lecture] W4S01-EssenceOfDispatchNot
2. [Lecture] W4S02-EssenceOfDispatch
3. [Lecture] W4S03-BasicClassMethods
4. [Lecture] W4S05-LearningFromMistake
5. [Lecture] W4S06-WhyTesting
6. [Lecture] W4S07-Debugging
7. [Live Exercise] Nautilus: Navigating Fast Inside Classes (check the subtitles here)
8. [Live Exercise] Spotter 2: Filter Results by Category (check the subtitles here)
9. [Live Exercise] How to load code from repository (check the subtitles here)
10. [Live Exercise] How to load projects (check the subtitles here)
11. [Live Exercise] Nautilus: An overview of Refactorings (check the subtitles here)
12. [Live Exercise] Nautilus: Using the Quality Assistant and Code Critic (check the subtitles here)
13. [Challenge] Challenge 2

You can access

1. the Week session slides
2. the Pharo Mooc videos. Pay attention they may be not in the same order - Check the Resources slide in the lectures to get the corresponding Pharo Mooc session.

Week 5: Inheritance

1. [Lecture] W5S01-InheritanceAndLookup-1-Inheritance
2. [Lecture] W5S02-InheritanceAndLookup-2-Lookup
3. [Lecture] W5S03-InheritanceAndLookup-3-Super-V2
4. [Lecture] W5S04-Design-ImplementingIfTrue
5. [Lecture] W5S05-MoreOnVariables
6. [Lecture] W5S06-Design-InstanceInitialization
7. [Live Exercise] Nautilus: Inheritance view (check the subtitles here)
8. [Live Exercise] Spotter: Scoping and Reducing Search (check the subtitles here)
9. [Live Exercise] Spotter: Search, Navigate and Preview Files (check the subtitles here)
10. [Live Exercise] Learning the Debugger (check the subtitles here)
11. [Live Exercise] How to find a bug? (check the subtitles here)
12. [Live Exercise] GTInspector: Inspect Files and Directories (check the subtitles here)
13. [Challenge] Challenge 3

You can access

1. the Week session slides
2. the Pharo Mooc videos. Pay attention they may be not in the same order - Check the Resources slide in the lectures to get the corresponding Pharo Mooc session.

Week 6: Plans For Reuse

1. [Lecture] W6S02-SelfSendsDiceHandle
2. [Lecture] W6S03-ClassMethodsAtWork
3. [Lecture] W6S04-SelfSendsArePlanForReuse
4. [Lecture] W6S05-HookAndTemplate
5. [Lecture] W6S06-Design-UseVsInheritance
6. [Live Exercise] Diffing and Merging in Pharo (check the subtitles here)
7. [Live Exercise] GTInspector: Build Custom Tab Views for your Objects (check the subtitles here)
8. [Challenge] Challenge 4

You can access

1. the Week session slides
2. the Pharo Mooc videos. Pay attention they may be not in the same order - Check the Resources slide in the lectures to get the corresponding Pharo Mooc session.

Week 7: Deeper into Lookup

1. [Lecture] W7S02-InheritanceAndLookup-5-LookupMetaclasses
2. [Lecture] W7S03-UnderstandingClassMethods
3. [Lecture] W7S04-AdvancedPointOnClasses
4. [Lecture] W7S05-Design-LearningFromRealExample
5. [Lecture] W7S06-AvoidIsNill
6. [Live Exercise] Spotter: The Preview pane (check the subtitles here)
7. [Live Exercise] Spotter: Search in Playground History (check the subtitles here)
8. [Live Exercise] GTInspector 3: Understand Pharo Internals by Inspection (check the subtitles here)
9. [Challenge] Challenge 5

You can access

1. the Week session slides
2. the Pharo Mooc videos. Pay attention they may be not in the same order - Check the Resources slide in the lectures to get the corresponding Pharo Mooc session.

Week 8: More on Dispatch

1. [Lecture] W8S01-Design-DoubleDispatch-Dice
2. [Lecture] W8S02-Design-DoubleDispatch
3. [Lecture] W8S03-Design-DualInterfaces
4. [Lecture] W8S05-OtherLanguages

You can access

1. the Week session slides
2. the Pharo Mooc videos. Pay attention they may be not in the same order - Check the Resources slide in the lectures to get the corresponding Pharo Mooc session.

Mini projects

• Miniprojects will have to be published on SmalltalkHub or github.com.
• Miniprojects will have to be covered by tests. Class/package comments will have to explain the design.
• You are asked to produce a log of actions each week and version it.
• Finally a small videos of 3 min will have to be produced and presented to the community.
• You can propose a topic.

• Tweet analysis
  • Description: The goal of this project is to develop a little application web or desktop that supports the analysis of tweets such as a frequency, vocabulary analysis. Search, statistics and visualisation are possible.
  • First tasks: check the API proposed by Tweeter, look at the example provided in Roassal (that you can find in the Moose http://www.moosetechnology.org distribution) and in the agile visualisation book, sketches some analyses such as the distributions and trends about a topics.
  • Possible contacts: Offray Valdimir Luna Car is a data journalist hacking in Pharo. You can contact him on the Pharo mailing-list or Discord. Alexandre Bergel the author of Roassal can be contacted too.
  • Link and resources: Have a look at the Zinc chapter in Entreprise Pharo, Agile visualisation and the Spec UI framework book available at http://books.pharo.org. Some indian students did a similar projects and they show it on youtube.
• RPG: FireEmblem/Disgaea using Bloc
  • Description: The goal of this project is to develop a turn-based RPG where a team of characters can attack a team of opponents on a 2D map in a Disgaea/Fire Emblem way.
  • First Tasks: Check the Bloc booklet below, check the CTGrid package, check some graphics from the opengame art database (https://opengameart.org/content/roguelikerpg-pack-1700-tiles), design a team and characters properties such as (Attack, Lifepoint, Magic points, Move distance), define objects responsible for the battle resolution.
  • Possible contacts: Stéphane Ducasse and Clément Béra.
  • Links and resources: Read the Bloc MemoryGame booklet http://books.pharo.org. Characters can be imported from: http://gaurav.munjal.us/Universal-LPC-Spritesheet-Character-Generator/. You can have a look at the Container/CTGrid datastructure available at: http://smalltalkhub.com/#!/~StephaneDucasse/Containers or 2DArray.
• Sprites Importer and manager
  • Description: The goal of this project is to (1) be able to import sprites from for example the opengameart community, (2) be able to load/edit/save levels and worlds. Map elements can be imported from: https://opengameart.org/content/zelda-like-tilesets-and-sprites https://opengameart.org/content/roguelikerpg-pack-1700-tiles.
  • First Tasks: Check the sprite challenge in the Pharo mooc. Define an importer that can import sprites of different projects. Verify that you can load different projects. You should be able to display the graphical elements and provide a mapping so that you can refer to them in maps. Have a look at the CTGrid package. The edition of maps can be made by associating a character with a graphics and to edit maps in ascii. This is nice to save maps. You should be able to load/edit/save maps. Using STON (the textual serialiser) you should be able to save worlds and their associated graphics. We should be able to attach a new set of graphics to a given map (like trees in different seasons). Now you can also have a graphical editor that can let the user define its map by dragging and dropping graphical elements from a palette. For this you should have a look at the Bloc booklet. (https://opengameart.org/content/roguelikerpg-pack-1700-tiles). C
  • Possible contacts: Stéphane Ducasse and Clément Béra.
  • Links and resources: To display the map you can use Bloc (Read the Bloc MemoryGame booklet http://books.pharo.org) or plain Morphic. To manage the map, you can have a look at the Container/CTGrid datastructure available at: http://smalltalkhub.com/#!/~StephaneDucasse/Containers or 2DArray.
• Improving tiny chat
  • Description: Tinychat is an exercise in the Pharo mooc. Lot of improvements are listed in the chapterhttp://mooc.pharo.org.
  • First Tasks: Read the tinychat exercise. Implement some of the extensions proposed and come up with your own. We could also have a web version using Seaside (see http://book.seaside.st).
  • Possible contacts: Olivier Auverlot (olivier.auverlot@gmailcom) and Stéphane Ducasse.
  • Links and resources: Read the Teapot Chapter in the Entreprise Pharo book available at http://books.pharo.org
• Discord analysis
  • Description: The goal of this project is to develop a little application (web or desktop) that supports the analysis of discord discussion. Contact with a researcher on the topic is possible. The code of a first tool based on Pharo 70 is available at: https://github.com/estebanlm/record
  • First Tasks: Read the code of the application. Read some of the example of Roassal in the book agile visualisation, familiarise yourself with Spec. You can propose word clouds, display evolution of discussions, characterise discussions (number of participants, length of the discussions, vocabulary used in a discussion....).
  • Possible contacts: Esteban Lorenzano and Stéphane Ducasse
  • Link and resources: Have a look at the Zinc chapter in Entreprise Pharo, Agile visualisation and the Spec UI framework book available at http://books.pharo.org.
• Game Collector App
  • Description: The goal of this project is to develop a little application (web or desktop) that supports the management of games (PS3, PS4, PS2, Wii). Describing games, managing different collections such as the games lent, that we are looking for, ... In addition it would be good to expose the collection on the web. Saving the collection can be done using the STON serialiser. Now other means such as using Voyage to talk to MongoDB is a possibility (Check the Voyage booklet https://books.pharo.org).
  • Link and resources: Have a look at the Spec UI framework book available at http://books.pharo.org for a desktop version. For a web solution http://book.seaside.st offers a free book on the seaside web frameworks - with REST integration.
• Books Collector App
  • Description: The goal of this project is to develop a little application (web or desktop) that supports the management of books. Describing books, managing different collections such as the games lent, that we are looking for, ... In addition it would be good to expose the collection on the web. Saving the collection can be done using the STON serialiser. Now other means such as using Voyage to talk to MongoDB is a possibility (Check the Voyage booklet https://books.pharo.org).
  • Link and resources: Have a look at the Spec UI framework book available at http://books.pharo.org for a desktop version. For a web solution http://book.seaside.st offers a free book on the seaside web frameworks - with REST integration.
• Sokoban using Bloc
  • Description: The goal of this project is to develop a sokoban game. The application should be able to load levels, collect points... Nicely decoupling the UI from the game model should be considered.
  • Possible contacts: Stéphane Ducasse and Aliaksei Syrel
  • Link and resources: Read the Bloc MemoryGame booklet http://books.pharo.org. https://juliendelplanque.be proposes a Pharo model for a miner and it may be useful to have a look at it. You can also have a look at the Container/CTGrid datastructure available at: http://smalltalkhub.com/#!/~StephaneDucasse/Containers or 2DArray.
• Contact and Prospect Manager App
  • Description: The goal of this project is to develop a little application (web or desktop) that supports the management of contacts and prospects. Describing contacts, import vcards, managing different collections. In addition it would be good to expose the collection on the web. Saving the collection can be done using the STON serialiser. Now other means such as using Voyage to talk to MongoDB is a possibility (Check the Voyage booklet). There is a start of the contact manager in the Pharo mooc exercises. This project should be extended to support prospects i.e. when you want to sale something you should describe better your contacts, their context, their role in a company, add some alarms to recontact them but also keep a log of the contact sessions. Such data can be shared between different sales persons. Now a sales may not want to share all its contacts and prospect with other sales.
  • First Tasks: Implement the simple exercise. Read the beginning chapter of the Seaside book.
  • Possible contacts: Stéphane Ducasse
  • Link and resources: Have a look at the Spec UI framework book available at http://books.pharo.org for a desktop version. For a web solution http://book.seaside.st offers a free book on the seaside web frameworks - with REST integration. A web version looks adapted to share prospect and contact between people.
• Minesweeper using Bloc
  • Description: The goal of this project is to develop a Minersweeper game. The application should be able to load levels, collect points... In addition, the placements of the bomb should not be random. The user should not be in a situation where he cannot deduce if there is a bomb or not. https://juliendelplanque.be proposes a Pharo model for a mine sweeper and it may be useful to have a look at it.
  • Possible contacts: Stéphane Ducasse and Aliaksei Syrel
  • Link and resources: Read the Bloc MemoryGame booklet available at http://books.pharo.org.
• Miner using Bloc
  • Description: The goal of this project is to develop a Miner game. The application should be able to load levels, collect points....https://juliendelplanque.be proposes a Pharo model for a minesweeper and it may be useful to have a look at it.
  • Possible contacts: Stéphane Ducasse and Aliaksei Syrel
  • Link and resources: Read the Bloc MemoryGame booklet available at http://books.pharo.org.
• Miniworld to learn path finding algorithms
  • Description: The goal of this project is to be able to study different AI algorithms related to path findings (depth-first, *Star, breath-first). We would like to have a 2D map such as the one in 2D game (sokoban, old zelda). On such a map each tile can have properties (cost to cross it, elements). Then we can build different algorithms starting from a place and looking for an exit taking into account obstacles (river, trees) or paths. The people using this miniworld should be able to inspect the algorithm and the world graph to understand the way the algorithm is working.
  • Possible contacts: Stéphane Ducasse and Aliaksei Syrel
  • Link and resources: The graphics can be rendered using plain Morphic or Bloc. Read the MemoryGame booklet http://books.pharo.org.
• Improving Wizard Battle Arena
  • Description: The goal of this project is to enhance the Wiazard Battle Arena game developed by C. Béra. https://github.com/clementbera/wizard-battle-arena The game should be able to load levels, collect points, have bonuses. An extended version could be to have a distributed version where we can play on multiple computer.
  • Possible contacts: Clément Béra and Stéphane Ducasse
  • Link and resources: Contact clement Bera https://clementbera.wordpress.com. Contact Noury Bouraqadi for his network discovery library called Ubiquitalk.
• AI for RPG combats
  • Description: The goal of this project is to develop an AI for RPG game such as fire Emblem where a team should beat opponents. An important design question is whether the AI knows the characteristics or not of the player team in term of strength, weapons and abilities. When we do not know the characteristics of the ennemies we should adapt and learn by remembering which opponent did what damage and how. Creating a small UI would be a plus but the output of a AI can be plain text.
  • First Tasks: Design characters (strength, attack, lifepoints, magic points), weapons (range, damage). Start to design objects responsible to represent a possible strategy like all attacking the same. Then we should find way to represent kind of rules to decide what to do. It may be interesting to use fuzy logic to help taking decision. Look at https://en.wikipedia.org/wiki/Fuzzy_logic and
  • Possible contacts: Stéphane Ducasse
  • Link and resources: Read the Bloc MemoryGame booklet http://books.pharo.org.
• Magic Deck builder App
  • Description: The goal of this project is to develop an App to manage magic card collection or decks. The player should be able to import a set of cards and build several decks with it. Validation rules such as no more than 4 cards of the same types should be enforced. Importing the information found on online database http://gatherer.wizards.com/Pages/Default.aspx using scraping approach as described in the booklet Scraping HTML uzing XPath available at http://books.pharo.org.
  • Link and resources: Have a look at the Spec UI framework book available at http://books.pharo.org for a desktop version. For a web solution http://book.seaside.st offers a free book on the seaside web frameworks - with REST integration.
• Snake Competition Client Server
  • Description: The goal of this project is to develop the client and server for the following competition systemhttps://stembolthq.github.io/battle_snake/. The renderer can be done on the web or inside Pharo using a 2D map. You should contact Jerry Kott jkott@cincom.com for help and information.
  • Link and resources: Read the Bloc MemoryGame booklet http://books.pharo.org.
• Client/Server HTTP for the elevator competition
  • Description: The goal of this project is to develop the client and server for the following competition systemhttps://github.com/xebia-france/code-elevator. The idea is that clients should code the logic to bring people from stair to stair. The server side schedules people waiting in front of the elevator and monitor each client and give different points to them showing a dash board of the competiting teams.
  • Link and resources: Reading the Zinc HTTP chapter on the Pharo Entreprise book will definitively help http://books.pharo.org. In addition the display for the result of the competiting teams can be done with Seaside http://seaside.st.
• OpenPonk
  • Description: The goal of this project is to develop some plugins for the OpenPonk modeling platform.
  • Link and resources: Talk to Peter and Prof. Pergl about it.
• Pillar renderer
  • Description: Pillar is document processing system developed in Pharo. The books, slides of this lectures are defined using Pillar. The idea of this project is to provide a live rendering system so that the writer can see a rendered version of what he is typing. In addition clicking on a graphical element should jump to the text. A first little experiment was made in the Pillar-Renderer package and can be loaded from the pillar repository. MCSmalltalkhubRepository owner: 'Pier' project: 'Pillar' user: '' password: ''. The current experience is using Morphic the default and old graphical framework. Using Bloc the future graphical framework is an option.
  • Link and resources: https://github.com/pillar-markup/pillar. Check the discussion in the Pharo mailing-list https://mail.google.com/mail/u/0/#search/pillar+editor/15e1d8bc2bbee23c . Contact stephane.ducasse@inria.fr for guidance. Read the chapter on double dispatch and the visitor design pattern. Ask Stephane Ducasse.
• Improving the Pillar HTML/epub outputter
  • Description: Pillar is document processing system developed in Pharo. The books, slides of this lectures are defined using Pillar. The idea of this project is to improve the HTML outputter as well as the epub one.
  • Link and resources: https://github.com/pillar-markup/pillar. Contact stephane.ducasse@inria.fr for guidance. Read the chapter on double dispatch and the visitor design pattern. Ask Stephane Ducasse.
• Surface Designer
  • Description: The goal of this project is to create a chip surface designer and simulator similar to the game Engineer of the people, but with infinite drawing areahttp://www.blakeohare.com/article/kohctpyktop https://www.youtube.com/watch?v=gG9utx6x0rY http://www.zachtronics.com/kohctpyktop-engineer-of-the-people/.
• macroassembler
  • Description: The goal of this project is to develop a macroassembler and simulator for a single-instruction computer https://pragprog.com/magazines/2012-03/the-nor-machine.

Download Pharo

We will use Pharo 50 as the Pharo Mooc. Now you are free to use Pharo 6.1

About

Stéphane Ducasse

Stéphane Ducasse is directeur de recherche at Inria. He leads the RMoD team. He is expert in two domains: object-oriented language design and reengineering. His works on traits have been introduced in AmbientTalk, Slate, Pharo, Perl-6, PHP 5.4 and Squeak. They have also influencedJavaScript, Scala and Fortress. Stéphane is also expert on software quality, program understanding, program visualisations, reengineering and metamodeling. He is one of the developers of Pharo. He is also one of the developers of Moose, an open-source software analysis platform. He created Synectique a company building dedicated tools for advanced software analysis. Stéphane wrote several books on programming learning and other topics such as web programming.