Pharo Launcher : What? How? #PharoInProgress

reposted from jigyasagrover.wordpress.com/pharolauncher-tutorial-what-how-pharoinprogress

This tutorial has been included as a chapter in  Pharo In Progress.



This post aims to provide a basic overview of what PharoLauncher is and give a step-by-step approach on how to use this application of great advantage.

Overview

Pharo is an open source implementation of the programming language and environment Smalltalk. Pharo is not Smalltalk. Pharo is Smalltalk-inspired.

Pharo offers strong live programming features such as immediate object manipulation, live update, and hot recompilation. Live programming environment is in the heart of the system. Pharo also supports advanced web development with frameworks such as Seaside and more recently Tide.

The official Pharo website defines it as: ”Pharo is a pure object-oriented programming language and a powerful environment, focused on simplicity and immediate feedback (think IDE and OS rolled into one). ”

Pharo relies on a virtual machine that is written almost entirely in Smalltalk itself. Pharo environment is its own little world, designed around a conception of a computer with a minimal operating system and populated with living objects. A Smalltalk implementation is composed of an image (binary code), a major source file and a ‘changes’ file. The image is called Virtual Image (VI) because is independent of the platform you use for running Smalltalk. Smalltalk systems store the entire program state (including both Class and non-Class objects) in an image file. The image can then be loaded by the Smalltalk virtual machine to restore a Smalltalk-like system to a prior state.

As Pharo is open source, it growing rapidly owing to the contributions of people all around the world. Each day we have a new update of the image of Pharo which makes it cumbersome to keep track of updates. It becomes quite a task when one has to download a new image seperately each he/she plans to work on something having the latest issues fixed, new features added etc. That’s where the PharoLauncher comes in the picture. Pharo Launcher, a cross-platform application that

  • lets you manage your Pharo images (launch, rename, copy and delete);
  • lets you download image templates (i.e., zip archives) from many different sources (Jenkins, files.pharo.org, and your local cache) and create new images from any template.

The idea behind the Pharo Launcher is that you should be able to access it very rapidly from your OS application launcher. As a result launching any image is never more than 3 clicks away. “PharoLauncher” is useful to a user who develops and needs to constantly switch between images. PharoLauncher is also a very handy tool to download specific image update versions if you want to reproduce or fix Pharo bugs.Pharo Launcher is a Pharo-based application allowing you to manage a list of images (download, rename, delete) and switch between them without aditional tools.

Downloading/Installing PharoLauncher

As discussed earlier about the rapid evolvement of Pharo , kindly check out http://www.pharo.org/download to get the latest download/install instructions for Pharo Launcher.

Linux Ubuntu:

(http://pharo.org/download#ubuntu) Ubuntu users can use the dedicated ppa to install Pharo

sudo add-apt-repository ppa:pharo/stable
sudo dpkg --add-architecture i386
sudo apt-get update
sudo apt-get install pharo-launcher

If you don’t have the add-apt-repository command, install the software-properties-common package and try again. If you are on a server (no GUI), you can get a Pharo Virtual Machine by installing pharo-vm-core.

On Ubuntu, the Launcher is installed as /usr/bin/pharo, so you can type the following command on the terminal to start the Pharo Launcher.

pharo 

ArchLinux :

(http://lists.pharo.org/pipermail/pharo-users_lists.pharo.org/2014-March/010932.html)

$ yaourt pharo-vm-latest
$ pharo /path/to/your/image

There’s also a pharo-launcher package that depends on pharo-vm:

$ yaourt pharo-launcher
$ pharo-launcher

Windows:

Download and install the executable from the link provided here.

MacOS:

Use the link (http://files.pharo.org/platform/launcher/latest.dmg)to install Pharo Launcher on Mac system. After installation , you’ll observe that the Launcher is installed in /Applications.

Using PharoLauncher

Launch the Pharo launcher image using the platform-specific VM. The image below depicts how a PharoLauncher looks like when it is opened.

pharolauncher_edited_new

The screen displayed initially has been divided into two parts.

The left part ‘Existing Images’ displays the images already created by the user. Initially after the installation the left side with local images is empty. Whereas the the right side is the ‘Templates’ section which displays the image templates from various resources available for download from the internet. The ‘Existing Images’ section has 3 buttons : Launch, Delete and Refresh. The ‘Templates’ section has 2 buttons : Create Image and Refresh.

At the bottom of the launcher we have the buttons for quit and settings.

Select the image you wish to work on from the list and the sources provided in the ‘Templates’ section and download it. For instance you can download “Pharo4.0 (beta)” from the options provided which is the latest image as of today. By clicking on the ‘Create Image’ button at the top right corner.

Note that also the images from contribution CI are available. So you can easily download “Artefact”, “Moose”, … images according to your choice.

It will download the image into a specific directory somewhere in your users home directory. Each image gets an own folder. Use the “Show in folder” menu item to open this location.

The location of the images can be changed through the ‘Settings Browser’ option located at the bottom-right corner. Go to the ‘Open Settings’ > ‘Location of your images’. Now enter the desired path in the place provided as shown in the figure.

location

After ‘Creating an image’ , a dialog box appears which asks you to give a name to the image as shown in figure below.

rename

After entering the suitable name , the image is displayed in the ‘Existing Images’ section.

myimage

To launch the image, simply select your option and click on the ‘Launch’ button located at the top right corner of the ‘Existing Images’ section and voila ! You have the pharo image of your choice running with the name of your choice.

myimg

You could watch this video on Pharo Launcher by Kilon Alios to get a clearer view (https://www.youtube.com/watch?v=fNim2Yxs320) Resources to explore further:

Do like the post if it was helpful. For any queries/suggestions please comment below. Thank You

Continue Reading Pharo Launcher : What? How? #PharoInProgress

Improve the command line tools of the sTeam collaboration platform

First of all, I really thank Google for organizing such an event for students in the summer and I am fortunate to be a part of such a program. I would also like to thank FOSSASIA for accepting my proposal for the project and for providing me with the experience of working with them.

When you see your name on the list

Name on the list? Google’s server being stacked up with lots and lots of request, Students impatiently clicking the refresh button to see whether their names are present in the list, a lot of students, a lot of projects, and suddenly, that one refresh, when the list loads with the projects matching the student names. (CTRL+F) ”Trilok Tourani” and there it was,

  • Organization : FOSSASIA
  • Project : Improve the command line tools of the sTeam collaboration platform
  • Student : Trilok Tourani
  • Mentors : Martin Bahr(Working mentor) , Chris Angelico, Aruna Herath, Markus(Backup mentors)
  • Status : Accepted

Dumbstruck for a minute, but when it hit me, that I got selected, the happiness was beyond what I had expected. I went on the IRC and thanked my mentors. All I knew was I had a project in hand and a long way ahead to perform beyond their expectations.


About the project

What is sTeam?

sTeam is a collaboration platform which helps people to share their documents, chat with them, have a look at their virtual workarea, and ease the sharing/developing in big groups. You can also look at the current development on the sTeam web interface here. It is still in the development phase, so please feel free to provide us with any ideas to improve. To know more about sTeam, please visit societyserver.

sTeam is completely built on pike programming language. To know more about pike programming, please visit Pike. If you already know about pike, and are good at it, please visit Fossasia’s IRC channel #fossasia and ask for tasks/bugs on this project to solve right away. If you are looking for something other than sTeam, FOSSASIA has a wide range of projects in various fields, and also welcomes any new project ideas.


My part of the project

I would like people to know the kind of work that I am doing currently for sTeam and show them how interesting it is to develop for it.

My project is to develop the command line tools to ease the work for the developers, and people who choose to work with command line, over a web interface.

These tools include,

  • Exporting your documents to your Github repository with just a command.
  • Importing document from Github right into sTeam for people to see.
  • A easy to use debug client that helps you while developing for this platform, or to see the various documents/containers you have in which room, move them, copy them, use them, all with commands similar to the Linux command line.
  • A way of to edit your documents directly with command line editors, without having to go to the web, type in the url, clicking on a document, and then finally editing it.
  • Chat with your friends/group members over the IRC.
  • and more being added to the list….(Please contact us if you have any)

These tools are already built up, but with more development, they will be very efficient and easy to use commands which a normal user can type in and get things done, and this is where my part comes in.

For some of these tools, which are already built, some development is needed. While some other tools, I have to develop by myself and enhance the command line usage for sTeam.

These are few of the commands with their screenshots to help you understand exactly what these tools are meant for,

The sTeam debug client

The editing documents client,

and edit the document in a simple command-line editor (used vim here),

Exporting documents from sTeam to git (version-wise)

Importing documents to sTeam from git (version-wise)

If you really like what I am doing, or are interested in developing for sTeam, please join our IRC channel #fossasia or join [email protected] .

If you are looking for some other project, FOSSASIA has a lot of projects to be worked on. Please visit FOSSASIA for more info.

Continue Reading Improve the command line tools of the sTeam collaboration platform

searchQuick Apprise: FOUR #GoogleSummerOfCode #FOSSASIA

banner-gsoc2015.png.pagespeed.ce.1-XG35qq3R8SQJ5DGgL9

The intended “searchQuick” (sQuick) is an application to enable a user to search a set of books or texts, like an encyclopedia, or some other topical book collection offline built in the open source platform Pharo 4.0.

header



After indexing the content and the next task that was covered was searching for the user input string. The #queryString: does a fantastic job as of now.
The search results were printed in a scroll-able pane by iterating through a loop so as to cover each and every existence of the desired string. The search results window also enables the user to view the content of the chosen file.

02Search Results Display

Acting on the suggestion of my mentor, I have also loaded the Pharo image with text versions of large books (Thank You Project Gutenberg 🙂 )  to test the working of the search function.

UPCOMING

  • GUI Modification
  • Integrated Exhaustive Testing
  • Addition of help/tutorial

PS: The GUI of the application is under constant evolvement, Kindly ignore the poorly structured window 😛

Stay tuned for more…
Post any queries , will be happy to help 🙂


Continue Reading searchQuick Apprise: FOUR #GoogleSummerOfCode #FOSSASIA

Knitting machine abstractions for Knitlib

Hello, during the last weeks we have been working on Knitlib and Knitpat, a knitting machine control library and a standardized format that allows for exchange and storage of patterns.

In order to achieve a common platform for knitting machine development we have the need to abstract away implementation details that can difficult the generic usage of the lib, while keeping extensible and powerful control features. Among the most important abstractions developed for Knitlib is the Knitting Machine Finite State Machine, an abstract representation of the procedures needed to operate a knitting machine.

BaseKnittingPlugin
BaseKnittingPlugin, the basis of knitlib’s machine knitting controller plugins.

The architecture of Knitlib allows for easy integration of different knitting machine plugins for varied use cases, hardware, and software protocols. All functions of the plugin are non blocking except for .knit(), which is blocking due to the physical interaction needed in order to execute this command. To ease usage and to enable more versatile behaviour from the .knit() function, without limiting the interaction facilities needed for operation, the callback infrastructure allows for blocking and non-blocking callbacks from the Plugin to the machine operator (the Knitlib client), such as Information, Warnings, Error Notifications or Mechanical Required Actions (moving spools, switches, needles, etc). Callbacks abstract away the notification and interaction paradigms from the plugin, allowing for simpler behaviour, a more elegant design and ease of testing. Callbacks also allow for future plugins to not take care into implementing user interfaces, but to focus on functionality.

The pending remaining challenge is to standardize configuration options, flags and settings in order to allow for UI that respond to each plugin requirements and options, and to specify which features are supported on each machine plugin. Insofar, most of the standardization has been done on Knitpat, but some specifications such as physical resource assignation (Serial Ports, input streams, etc) are still to be implemented soon.

Thank you, and I hope this article helps you to understand the software architecture and design patterns of the implementation of Knitlib.

Regards,

Sebastian

Continue Reading Knitting machine abstractions for Knitlib

GSoC 2015 with FOSSASIA – Mid-term report

TL;DR No Chicken Little, the sky is not falling.

Well. I’ve been selected for GSoC under organization FOSSASIA and I am working on the project sTeam Collaboration platform, mentored by awesome guys Martin and Aruna.

It is mid term already and as planned I am half way through the project. If you haven’t seen my past blogposts, go check them out to get clear idea of the project.sTeam is a document based collaboration platform. There is already an existing web interface for the platform. Interestingly REST APIs are being developed for the same and we planned to rewrite the web interface with AngularJS and make calls to the REST APIs.

Technology stack

  • bower for easy management of external modules. There are a lot of sub modules which are to be loaded and are not part of the angular itself. Though, some of the modules are bloated. The unnecessary files will be removed by using bower prune task with gulp.
  • angular-ui-router for handling deep nested routes. Interesting thing is, angular-ui-router works on state based concept and is very handy to maintain and route to certain state.
  • angular-ui-bootstrap gives us easy to use, clean and responsive UI blocks.
  • angular-local-storage We use it for saving the user’s login credentials and are sent to the API with every REST based call. This would be changed in future and session maintenace should be developed.
  • textAngular is lightweight and two way bound WYSIWYG Text Editor for handling plain text files. It can also handle source code, markdown, etc ..
  • ng-audio and ng-video for viewing audio and video files respectively.

Views

  • login and workarea are two base templates. And the router loads one of these based on the login credential value stored in local storage.
  • With workarea as base template, at this level, two nested views. Groups, which displays the groups which the user is part of and Private, where the user’s private documents are displayed.
  • The options view has various options like, permission management for the current level, copy, link, etc.. and also create room and document modals.
  • comments view fetches the comments for the current path. It is hidden if no permission to comment.

Controllers

  • loginCtrl for passing the credentials to the API, authenticate and parellely store them in localStorage. And all the other calls will use the stored value along with its payload. You know, REST is stateless! Session management is scoped to the API and is planned for future.
  • handler has functions for CRUD operations on the API. The functions do GET, PUT, POST, DELETE, .. on the passed paramater (which is the path to the room/document) and will return the value.
  • router handles the routes. It has base states with views loaded into each states with its own templates and controllers.
  • The run methods load are used for state change control.
  • workareaCtrl handles the scope for options loading and current level display in breadcrumb.
  • workspaceCtrl fetches and controls the main workspace which has the rooms, documents and containers displayed.
  • config has the hostname where the sTeam is deployed and change here is reflected systemwide for easy deployment.

Road ahead

  • Depending on the type (room/document), the appropriate view should be loaded and when document, the viewer/editor wrt to the mime type should be loaded. Follow the issue here – https://github.com/dolftax/sTeam-web-interface/issues/10
  • Implement search, document/room sorting based on Author, Title, document type and date.
  • Setup right sidebar which lists all the rooms (for easy navigation).
  • Settings popup for changes to attributes of the objects.
  • Automate tasks with certain gulp modules – gulp-angular-templatecache, gult-concat, gult-lint, gulp-uglify, ..
  • Write unit tests with mocha and chai.
  • Tidy up and add more documentation, which is already being done here –https://github.com/eMBee/sTeam/wiki/Installation-steps

Apart, we do scrum meet everyday. Check out the logs – http://dpaste.com/2A3J121

Currently, node-static module is used to serve the app and our development server is hosted in azure – http://steam-web.azurewebsites.net/

Note: The project is heavily under development and things might break.

Sign-up API is not implemented yet. Find some of the working screenshots below

Login

Private workarea

Groups

Create room

Create document

Future plans

The REST APIs are under development and a lot of features are yet to be developed. I have a brief listing of the yet to be developed APIs and the list grows eventually as we figure out something is missing.

Thats all for now. Will get back soon!

Continue Reading GSoC 2015 with FOSSASIA – Mid-term report

API Integration

My FOSSASIA project is taking a big transitioning step from the starting plan. In milestone 3 and 4, rather than focusing on statistical retrieval and API documentation wepapp, my mentors – Mario (@mario) and Andreas (@andibraeu) are guiding me towards integrating fossasia api data in other services. The main goal remains the same though : getting more people to use and to know about the API.

Integrating our set of data into external services can be tricky, but this is also what makes the task so exciting. Currently, we’re already started the integration process into loklak, a distributed searching & harvesting server. You can find out more about loklak via their well detailed about page. But the plan doesn’t stop there. We’re targeting popular web platforms : WordPress, Drupal, Github Pages.. so that users can access our data with ease, and use our services / plugins in their websites within simple steps. That would be a big win for us, so I’m very impatient to get going with the code to brings these ideas to life.

References :

Continue Reading API Integration

Importance of a pattern editor for knitting applications

Hi Everyone, I am Sameera Gunarathne who is a participant for GSoC ’15 for FossAsia under fashion and technology. I am developing web based GUI for knitting applications. Today I am going to talk about importance of integrating a pattern editor inside knitting applications and little bit about my work on the pattern editor implementation.

Why knitting application should have a pattern editor? It’s to simply give the user capability of doing all the editing work on the pattern before it is sent for knitting. Therefore user will be able to proceed the whole knitting process using one application. User doesn’t have to use a separate application to edit the pattern and then import the pattern to the knitting software to get knitting done. Also most these pattern editor applications are commercially available which means user has to pay for the application and its updates. So that’s extra money. Some examples for available pattern editor softwares are knitbird , envisioknit , stitchmastery  etc.

KnitBird application
KnitBird application

So what about open source knitting machine software with a feature rich pattern editor? Cool right. I am working on integrating feature rich pattern editor for the knitting web application that I am developing for FossAsia this GSoC. Following features are already added to the pattern editor implementation.

  • Getting a loaded pattern to a pixelated grid to give user a easily editable interface.[1]
  • Pixelated pattern can be generated from available yarn colours that used for knitting.[2]
  • Cropping tool for load necessary parts from the pattern.[3]
  • Rectangular/Free Hand selection of loaded pattern.[4]
  • Editing colour details of a selected area of the pattern.[5]
  • Drawing tool for the loaded pattern. [6]

User is given capability to regenerate the pattern according to the available yarn colours for the knitting. This functionality allows user to understand how the actual knitting output will be there with the available yarn colours. Below are the some of screen shots of current implementation.

Loaded pattern in pixelated grid
[1] Loaded pattern in pixelated grid
Pixelated pattern can be generated from available yarn colours
[2] Pixelated pattern can be generated from available yarn colours
Cropping tool
[3]Cropping tool
Rectangular selection
[4]Rectangular selection
Free Hand selection
[4]Free Hand selection
Editing colour details of a selected area
[5]Editing colour details of a selected area
Drawing tool
[6]Drawing tool
I am very much enthusiastic on the project and working hard to get a good outcome for the knitting web application implementation. See you with the next blog post update. Thanks :).

Continue Reading Importance of a pattern editor for knitting applications

FOSSASIA Google Code-In Students and Mentor at Googleplex Mountain View

Last week grand prize winners from FOSSASIA and other organizations that participated in Google Code-In 2014 attended a trip to the US accompanied by a guardian and a mentor. The grand prize trip is the crowning activity of Google Code In, the program organized by Google with the aim of introducing pre-university students to open source. I was fortunate enough to take part as the mentor representing FOSSASIA.

2014 was FOSSASIA’s first participation in GCI and it was a great success for us.

The trip kicked off on the evening of the 7th June with a ‘meet and greet’ at the hotel lobby. Stephanie Taylor and Mary Radomile from Google OSPO welcomed us. I met Namanyay Goel and Samarjeet Singh, the two winners from fossasia, and a bunch of other winning students and mentors. Groups of students were quick to engage in lively discussions, It was hard to believe that most of them met for the first time. I was glad to learn that both our winning students enjoyed the contest as much as I did. At the end of the two hours both students and mentors were holding on to some rewards from Google. As I was tired from the long flight I bid everyone an early goodbye to get a much needed sleep.

FOSSASIA Google Code-In 2014I met Namanyay and Samarjeet, Grand prize winners from FOSSASIA.

The next morning we met in the hotel lobby again. We were to spend the day in the Google headquarters in Mountain View. The San Francisco traffic delayed our buses a bit but we arrived at the Googleplex to a pleasant breakfast. In the morning we listened to talks from Engineers of Google projects Ara and Tango. A series of interesting questions from an enthusiastic audience followed each talk. Chris DiBona, the director of the Google OSPO presented winners their awards. After a lunch where students got to enjoy with Googlers from their respective countries, we were back for more talks. The one from Google’s rapidly evolving self driving cars, caught a lot of attention. We also got to visit the Google visitor center, where we met famous giant Androids, and to the Google store, where everyone bought a bunch of souvenirs to take back home.

Third day of the tour was the ‘fun day’. Each of us were to choose between visiting the Alcatraz island which was the home to the historic federal prison, the Exploratorium, a science and arts museum and a segway tour around San Francisco. About half of the group and I picked segways. We rode the brilliantly engineered machines around the city while our guide entertained us with interesting facts about the city. It was a novel experience for everyone. The three groups met for the lunch and set off to see the famous Golden gate bridge, where we spent the afternoon. A Yacht course across the San Francisco bay, during which we sailed under the Golden Gate, completed a day filled with amazing memories.

The final day was spent in the Google office in San Francisco. We got to listen to a talk about YouTube, which again followed some interesting questions and answers. Carol Smith introduced GSOC, the Sister program of GCI, to the students. Each of the mentors gave a brief introduction to their organizations. We were officially announced that GCI will continue in 2015 as well. The students presented Stephanie with a handmade thank you card inscripted by all of them, which I thought was pretty cool.

The trip was filled with both information and fun. It indeed was a Grand Prize. I hardly know how to thank Stephanie and co. for everything.

I hope, irrespective of being probably the best in their age, in their field, the winning students would stay humble and hungry for new knowledge. Looking forward to GCI 2015.

Link

See how GCI 2014 went: http://www.google-melange.com/gci/org/google/gci2014/fossasia

Continue Reading FOSSASIA Google Code-In Students and Mentor at Googleplex Mountain View

searchQuick Apprise: THREE #GoogleSummerOfCode #FOSSASIA

banner-gsoc2015.png.pagespeed.ce.1-XG35qq3R8SQJ5DGgL9

The intended “searchQuick” (sQuick) is an application to enable a user to search a set of books or texts, like an encyclopedia, or some other topical book collection offline built in the open source platform Pharo 4.0.

header



After the GUI was designed with minimal features, the next task was to develop the cardinal search function.

Indubitably, a well-run search application/engine requires indexing.

Search Application/Engine Indexing basically collects, parses and stores data to facilitate fast and accurate information retrieval.

That being, the index for sQuick was built using the Dictionary data structure in Pharo which works like HashTable of other programming languages/platforms.

index := Dictionary new.

Pharo describes a Dictionary as: “I represent a set of elements that can be viewed from one of the two perspectives: a set of associations, or a container of values that are extremely named where the name can be any object that responds to =. The external name is referred to as the key. I inherit many operations from the Set. “

The contents of the text files present in the current Pharo image were split at whitespaces and added to the index along with the corresponding file title.

tokens := ‘ ‘ split: aDocument contents.

The method #indexFiles was used to iterate over all the text files in the current Pharo image to index all the files before the searching begins.

Index

Dictionary Entries after File Content Indexing

The #queryString method has been temporarily build using #includesSubstring which matches the user input string with all the entries of the index and gives the result in an array form with #tally output as the number of search results.

Various test methods are now built to inspect the functioning of the methods designed. Continuous debugging is being done to check out and remove errors, if any 😉

UPCOMING:

  • Improve the indexing technique
  • Explore methods to quicken the search functionality
  • Integrate the search routine with the GUI already built
  • Design more test cases to develop a bug-free application

Stay tuned for more…
Post any queries , will be happy to help 🙂


Continue Reading searchQuick Apprise: THREE #GoogleSummerOfCode #FOSSASIA

TicTacToe Tutorial #FunWithPharo

reposted from jigyasagrover.wordpress.com/tictactoe-tutorial-funwithpharo

This tutorial has been included as a chapter in  Fun With Pharo!



Tic-tac-toe (or Noughts and crosses, Xs and Os) is a paper-and-pencil game for two players, X and O, who take turns marking the spaces in a 3×3 grid. The player who succeeds in placing three respective marks in a horizontal, vertical, or diagonal row wins the game.

Because of the simplicity of Tic-tac-toe, it is often used as a pedagogical tool for teaching the concepts of good sportsmanship and the branch of artificial intelligence that deals with the searching of game trees. It is straightforward to write a computer program to play Tic-tac-toe perfectly, to enumerate the 765 essentially different positions (the state space complexity), or the 26,830 possible games up to rotations and reflections (the game tree complexity) on this space.

t

So , here we make a Pharo version of this well-known game by using Morph. This post provides a step-by-step approach on how to go about building this simple application.

TTT2

A game package will be built having 3 subclasses :

  • TicTacToe
  • TicTacToeCell
  • TicTacToeModel

Initially , we have created TicTacToe a subclass of the Object class. The subclasses we will make will be combined in the package game as mentioned in the category: parameter.

Object subclass: #TicTacToe
instanceVariableNames: 'container model'
classVariableNames: ''
poolDictionaries: ''
category: 'game'

A category name is not required in order for the class to work, but you will not be able to access the class to make changes or to look at existing code unless you provide a category name. (The category name used can be a new category name or the name of an existing category.)

The poolDictionaries: parameter is seldom used and will not be discussed here, and the category: parameter specifies the category under which this class will be grouped in the system browser.

As we know, a class encapsulates data values and methods, and every object contains a set of the data values and can receive any of the methods as a message. The data values in each object are specified by providing a set of names of variables whose values will be an object’s internal data values. Each object has its own set of these values, and the set of data values for an object represents the object’s state (or value). The variables that contain the data values of an object are called the instance variables for the object, and the instanceVariableNames: parameter is a list of names, separated by blanks, for the instance variables. In the above code snippet , we have declared container and model as two instanceVariables.

The classVariableNames: parameter lists the identifiers that are the names of variables shared by the class and all of its objects. That is, there is only one set of these, and they are used by the class and all of its objects. Class variables (so called because they belong to the class, of which there is only one, rather than to the objects that are instances of the class) are rarely needed.

An example of a class variable that could be useful is in a case where we wanted a unique “serial number” to be assigned to each instance of the class as it is created. The variable containing the next available (or last used) serial number would appropriately be a class variable, and each time a new instance (object) is created the serial number would be recorded as an instance variable value in the object and the serial number in the class variable would be incremented. Thus, each object can be serially numbered as it is created (without using one of those nasty global variables!).

After executing the code above, class TicTacToe will exist. However, it will have no methods other than those that are inherited from class Object. To make it useful, we must add the methods that are needed for our implementation.

Adding methods to classes :

The subClasses interact by passing messages through objects only.

TicTacToe>>#initialize 
container := Morph new 
              layoutPolicy: TableLayout new; 
              color: Color transparent.
model := TicTacToeModel new:3.
self addRows.
self addControls.
^self.

The notation TicTacToe>>#initialize means that we have a method named initialize in the subclass TicTacToe.

In the initialize: method above , we have a container which is the instance of the class Morph (Morphic is the name given to Pharo’s graphical interface. ). We define the various attributes of the container such as layoutPolicy: and color:. model is another instance of the class TicTacToeModel which we will be creating further in this example.

self refers to the receiver of the message. It is usually used within a method to send additional messages to the receiver. self is frequently used when it is desired to pass the sender object (self), as a message argument, to a receiver who requires knowledege of the sender or who will in some way manipulate the sender.

In short, self refers to the object itself that defines the method.

TicTacToe>>#addRows
| rowMorph aCell rowCol |
1 to:3 do:[ :row |
rowMorph := Morph new layoutPolicy: RowLayout new.
1 to: 3 do: [ :col |
aCell := TicTacToeCell new.
aCell setModel: (model) row: row col: col.
rowMorph addMorph: aCell.
].
container addMorph: rowMorph.
]

The method addRows (the name is self explanatory) is used to add rows in the Tic Tac Toe grid. It declares temporary (local) variables rowMorph , aCell and rowCol which can’t be used beyond this method.

1 to:3 do:[ :row |

rowMorph := Morph new layoutPolicy: RowLayout new.

1 to: 3 do: [ :col |

aCell := TicTacToeCell new.

aCell setModel: (model) row: row col: col.

rowMorph addMorph: aCell.

].

The above code snippet works as a nested loop that runs thrice for each three rows to create a 3X3 grid as per requirement.

TicTacToe>>#addControls
| rowMorph newGameButton exitGameButton |
rowMorph := Morph new 
             layoutPolicy: RowLayout new; 
             color: Color transparent.
newGameButton := self createCtrlLabelled: 'New'    onClickExecutes: [self restart].
exitGameButton := self createCtrlLabelled: 'Exit'  onClickExecutes: [container delete].
rowMorph addMorph: exitGameButton.
rowMorph addMorph: newGameButton.
container addMorph: rowMorph.

This method adds controls to the game. The local variables are : rowMorph , newGameButton and exitGameButton.

rowMorph defines an instance of the class Morph which would be the placeholder for the two control buttons located at the top. The two control buttons are defined as New using the variable new GameButton which on click would restart the game , and Exit using the exitGameButton which on click would close the game. The buttons are created using a method createCtrlLabelled which we define next.

rowMorph addMorph: newGameButton adds the button to the Morph instance created earlier.

TicTacToe>>#createCtrlLabelled: aString onClickExecutes: aBlock
| aCtrlButton |
aCtrlButton := SimpleButtonMorph new label: aString.
aCtrlButton color: (Color black alpha: 0.2).
aCtrlButton extent: 120@50.
aCtrlButton on: #click send: #value to: aBlock.
^aCtrlButton.

TicTacToe>>#createCtrlLabelled: aString onClickExecutes: aBlock method makes a simple button using Morph adds label and control to it.

TicTacToe>>#open 
container openInWindow.

The open method defines as to how the game/TicTacToe class would open. Here we have defined it to open in a dialog box.

TicTacToe>>#restart
container delete.
Smalltalk garbageCollect.
TicTacToe new open.

It closes the game and calls for Garbage Collection (Garbage Collection (GC) is a form of automatic memory management. It finds data objects in a program that cannot be accessed in the future and reclaims the resources used by those objects.)

SimpleButtonMorph subclass: #TicTacToeCell
instanceVariableNames: 'parentModel rowNum colNum'
classVariableNames: ''
poolDictionaries: ''
category: 'game'

Here a subclass TicTacToeCell is defind in the SimpleButtonMorph class with parentModel , rowNum and colNum as the instance variables. This class defines the button for each cell of the grid.

TicTacToeCell>>#initialize 
super initialize.
self label: ''.
self extent: 80@80.
self color: Color yellow .
self on: #click send: #value to: (self onClickExecutionBlock).
^self.

This initialize method initialises the button size as 80X80 and gives it the color: yellow. An ‘onClick’ control is given to the button which then calls the onClickExecutionBlock method present in the same class.

TicTacToeCell>>#setModel: ticTacToeModel row: aRow col: aCol
parentModel := ticTacToeModel.
rowNum := aRow.
colNum := aCol.

The setModel: row: col: takes three arguments ticTacToeModel , aRow and aCol. The parentModel is assigned ticTacToeModel , roNum becomes the value of aRow and similiarly colNum has the value aCol.

TicTacToeCell>>#onClickExecutionBlock
^[
(self label size) == 0
ifTrue:[
self label: (parentModel updateAtRow: rowNum 
                Col: colNum).
parentModel checkWinCondition.
self extent: 80@80.
].
 ]

This method defines what should happen when each cell in the grid is clicked. At every click , the label of the cell is changed to X or O depending upon whose turn it is , the row numbers and coloumn numbers are updated in the parentModel and win condition is checked by calling the checkWinCondition method of the class TicTacToeModel defined next.

Matrix subclass: #TicTacToeModel
instanceVariableNames: 'filledCellCount currentFill winner'
classVariableNames: ''
poolDictionaries: ''
category: 'game'

A subclass TicTacToeModel is defined in the Matrix class with filledCellCount , currentFill and winner as the instance variables.

TicTacToeModel>>#initialize 
super initialize.
filledCellCount := 0.
currentFill := nil.
winner := nil.

This initialize methods defines that initially no cell in the grid is filled and there is no winner as of now.

TicTacToeModel>>#updateAtRow: r Col: c
currentFill == nil
ifTrue:[ currentFill := 'X'. ]
ifFalse:[
currentFill == 'X'
ifTrue: [ currentFill := 'O'. ]
ifFalse: [ currentFill := 'X'. ]
].
self at: r at: c put: currentFill.
filledCellCount := filledCellCount + 1.
^currentFill.

The updateRowAt: Col: method takes two arguments r and c used to update the currentFill and filledCellCount variables.

TicTacToeModel>>#checkWinCondition
filledCellCount >= 5 "for optimization. Win can occur minimum at 5th turn"
ifTrue: [
Transcript show: 'Yes'.
1 to: 3 do: [:idx |
self checkWinConditionInRow: idx.
self checkWinConditionInColumn: idx.
].
self checkWinConditionInDiagonals.
].
checkWinConditionInRow: rowNum
|set|
winner isNil
ifTrue: [
set := (self atRow: rowNum) asSet.
self checkWinConditionInSet: set
].
^winner.

The method checkWinCondition is self explanatory. It is used to check if we have a winner or not at every move.

TicTacToeModel>>#checkWinConditionInColumn: colNum
|set|
winner isNil
ifTrue: [
set := (self atColumn: colNum) asSet.
self checkWinConditionInSet: set.
].
^winner.
TicTacToeModel>>#checkWinConditionInDiagonals
|set1 set2 |
winner isNil
ifTrue: [
set1 := (self diagonal) asSet.
set2 := Set newFrom: {(self at: 1 at: 3). (self at: 2 at: 2). (self at: 3 at: 1)} asOrderedCollection.
self checkWinConditionInSet: set1.
self checkWinConditionInSet: set2.
].
^winner.
TicTacToeModel>>#checkWinConditionInSet: aSet
aSet size == 1
ifTrue: [
(aSet includes: 'X')
ifTrue: [
        winner := 'P1'. 
        Transcript open. 
        Transcript show: 'Player 1 is the winner!!'.
    ].

(aSet includes: 'O')

ifTrue: [
        winner := 'P2'.  
        Transcript open. 
        Transcript show: 'Player 2 is the winner!!'.
    ].
].

example2.

Now , we have made the game. To open the game , simply execute the following in the playground/workspace.

TicTacToe new open.

The messages : ‘Yes’ , ‘Player x is the winner’ will be displayed in the Transcript.

PS – This was just the basic implementation. I plan to improvise it further with graphics and other functionality/features.

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