![ARRAYS
• Arrays, like variables, dont need initialization
• temp = Array.new(10)
• puts temp.size or puts temp.length
• We can save variables of different type
• Values are saved as A = ['A','B','C'] or A[0] = 1 etc
SHORTCUT %w
%w is used in order to initialize arrays alternatively,
A = %w{ A B C }](https://image.slidesharecdn.com/rubypresentationupdated-151010091946-lva1-app6891/85/Ruby-Presentation-21-320.jpg)
![HASHES
• To initialize Hashes we use curly braces instead of braces
• In order to initialize a map :
"key => value"
Note : keys are unique, values are not
• temp = Hash.new
Hash Display
temp[:key]
If key does not exist, nil is returned](https://image.slidesharecdn.com/rubypresentationupdated-151010091946-lva1-app6891/85/Ruby-Presentation-22-320.jpg)
![LOOPS
• main body does not require curly braces { }
• Condition does not require parentheses
• Known loops are :
1. while[condition]-end, begin-while[condition]
2. begin – end until [condition]
3. for i in 0…j
next : is used in order to pass to the next value
redo : restarts the iteration of the most internal loop,
without checking loop condition.
If retry appears in rescue clause of begin expression,
restart from the beginning of the 1begin body.](https://image.slidesharecdn.com/rubypresentationupdated-151010091946-lva1-app6891/85/Ruby-Presentation-24-320.jpg)
Ruby Presentation
- 1. RUBY Introduction to Ruby Programming Language by Kostas Platis
- 2. “ ” I HOPE TO SEE RUBY HELP EVERY PROGRAMMER IN THE WORLD TO BE PRODUCTIVE, AND TO ENJOY PROGRAMMING, AND TO BE HAPPY. THAT IS THE PRIMARY PURPOSE OF RUBY LANGUAGE. Yukihiro Matsumoto Google Tech Talk(2008) •Created in 1993 by Yukihiro Matsumoto •Initially 2 names were proposed :“Coral” and “Ruby” •His aim was to create a programming language easy-to-use
- 3. DYNAMIC “Dynamic programming language is a term used in computer science to describe a class of high-level programming languages which, at runtime, execute many common programming behaviors that static programming languages perform during compilation.” wikipedia.com Ruby is a dynamic programming language
- 4. OBJECT-ORIENTED Ruby is pure object-oriented language and everything appears to Ruby as an object Even a class itself is an object that is an instance of the Class class Ruby is based on the concept of “objects” , classes , attributes and methods.
- 5. GENERAL PURPOSE Ruby is a programming language designed to be used for writing software in a wide variety of application domains like: • Server-Side(Ruby-on-Rails) • Web Servers • Common GUI Applications • Low-Level systems
- 6. FAMOUS APPLICATIONS WRITTEN IN RUBY Simulations NASA Langley Research Center uses Ruby to conduct simulations. 3D Modeling Google SketchUp is a 3D modeling application that uses Ruby for its macro scripting API. Robotics At MORPHA project, Ruby was used to implemented the reactive control part for the Siemens service robot. Web Applications Implemented in Rails
- 7. VERSIONS • Ruby 1.0: December1996 • Ruby 1.2: December 1998 • Ruby 1.4: August 1999 • Ruby 1.6: September 2000 • Ruby 1.8: August 2003 • Ruby 1.9: December 2007 • Ruby 2.1: December 2013 • Ruby 2.2: December 2014
- 8. RUBY INSTALLATION Ubuntu 1) Open Terminal 2) apt-add-repository ppa:brightbox/ruby-ng 3) apt-get update 4) apt-get install ruby 2.2 5) Done! Windows 1) Open www.rubyinstaller.org 2) Download Ruby 2.2.3 3) Install RubyInstaller
- 9. RUBY GEMS As most programming languages, Ruby offers a wide set of third- party libraries. Most of them are released in the form of a gem RubyGems is a package manager for the Ruby programming language that provides a standard format for distributing Ruby programs and libraries
- 10. RUBY RVM RVM(Ruby Version Manager) is a command-line tool which allows you to easily install, manage, and work with multiple ruby environments from interpreters to sets of gems. RVM is a programmer’s helping hand for : 1. Production RVM lets you deploy each project with its own completely self- contained and dedicated environment, from the specific version of ruby, all the way down to the precise set of required gems to run your application. With RVM, NO OTHER GEMS than those required are installed. Efficiency when working on complex applications
- 11. RUBY RVM 2. Testing RVM enables you to easily test both upgrade and escape paths very easily and consistently. With RVM, you can run a test suite, rake tasks, benchmarks and gem commands against multiple ruby versions at the same time. 3. Gem Management RVM has an extremely flexible gem management system called Named Gem Sets. RVM's 'gemsets' make managing gems across multiple versions of Ruby a non-issue. Note : RVM is for Ruby applications, *not just for Rails*! Any Ruby based application will benefit from your use of RVM.
- 12. RVM INSTALLATION Ubuntu 1. Open Terminal 3) curl –sSL https://get.rvm.io | bash 4) Done! Windows RVM is not developed for Windows. An alternative is pik (https://github.com/vertiginous/pik)
- 13. IRB Interactive Ruby Shell (IRB or irb) is a REPL for programming in Ruby. The program is launched from a command line and allows the execution of Ruby commands with immediate response, experimenting in real-time. irb is executed using the “irb” command. Use “exit” to exit irb
- 14. IRB We can use irb in order to evaluate a variety of expressions You can also invoke a single program with irb
- 15. RUBY IDE For Ruby Developing I personally use and recommend RubyMine (Developed by JetBrains) RubyMine is free for Students RubyMine Installation 1. https://www.jetbrains.com/ruby 2. Download and install RubyMine 3. Create JetBrains Account 4. Apply for Student licence in www.jetbrains.com/student 5. Open RubyMine and login using your account
- 16. IN GENERAL • Ruby files use the suffix .rb • Comments start with # • Multiple line comments use =begin , =end • nil(null in other programming languages) means that the object is an instance of the Nil Class • Blocks end using the “end” statement • Variables dynamically change their type
- 17. NAMING Ruby has some strange naming conventions 1. Local varibles, method’s parameters and method’s names are written in lowercase 2. Constants are written in capital letters 3. Global variables are prefixed with the dollar sign ($) 4. Field names are prefixed with the “at” sign "@" 5. Class names are prefixed with the “double at” sign "@@"
- 18. CLASSES & OBJECTS Class ClassName attr_accessor :var1,:var2 <methods> End Constructors are named “initialize(param1,param2…)” attr_accessor is used as getter,setter Inheritance is a thing Multiple Inheritance is not objectTitle = ClassName.new(param1,param2…)
- 19. METHODS def method_name(param_1,param_2...) <code> <code> <code> end • “return” is not necessary. The returned value is the latest changed variable • Method block ends with “end”
- 20. STRING CHARACTERISTICS • “n” is used as line breaker • If we want to use a variable name inside a string we just add #{variable_name} • Alternatively, we can use the + operator in order to unite 2 or more strings • Double quote vs Single quotes : Double quotes allow you to do string interpolation
- 21. ARRAYS • Arrays, like variables, dont need initialization • temp = Array.new(10) • puts temp.size or puts temp.length • We can save variables of different type • Values are saved as A = ['A','B','C'] or A[0] = 1 etc SHORTCUT %w %w is used in order to initialize arrays alternatively, A = %w{ A B C }
- 22. HASHES • To initialize Hashes we use curly braces instead of braces • In order to initialize a map : "key => value" Note : keys are unique, values are not • temp = Hash.new Hash Display temp[:key] If key does not exist, nil is returned
- 23. CONDITIONAL STRUCTURES • main body does not require curly braces { } • Condition does not require parentheses • If main body contains only one command, the command can go before the condition • Conditional structures are : if-elsif-else, Case-when (like switch-case) unless-else
- 24. LOOPS • main body does not require curly braces { } • Condition does not require parentheses • Known loops are : 1. while[condition]-end, begin-while[condition] 2. begin – end until [condition] 3. for i in 0…j next : is used in order to pass to the next value redo : restarts the iteration of the most internal loop, without checking loop condition. If retry appears in rescue clause of begin expression, restart from the beginning of the 1begin body.
- 25. CODE BLOCKS Ruby includes a pretty cool feature : The Code Blocks • We can call a method which has the same name but different body by using the yield command • Any code surrounded by curly braces is a block • The calling can include arguments called Block arguments {|arg1,arg2| code_including_args}
- 26. CODE BLOCKS Yeah…ok but whats the usage? 1. To keep things concise and understandable 2. To create more elegant code 3. To iterate lists (especially in Rails)
- 27. ITERATORS .each method for arrays & hashes (block) times & upto(-number-) for numbers Iterators can be used as blocks
- 28. I/O 2 main ways to output 1. puts (like println in Java) 2. printf (Like in C/C++) gets is the main way to input data
- 29. EXCEPTIONS Are handled using begin-rescue Some known Exception subclasses are: NoMemoryError ScriptError StandardError SystemExit SystemStackError
- 30. WHY RUBY? 1. Ruby allows the programmer to do things fast (less code – but takes time to learn). That’s why Ruby programmers are happy 2. Open-Source (Hundreds of recourses – everything is free! – gems usage) 3. Everything is free! Gems usage save time and money 4. Ruby On Rails (Rails conventions)
- 31. RESOURCES www.ruby-lang.org (Ruby Official Site) www.tutorialspoint.com/ruby (Examples provider) www.rubylearning.com (Useful Tutorials) www.rubyinstaller.org (Installer for Windows) www.jetbrains.com/ruby (RubyMine IDE)
- 32. THANK YOU! Kostas Platis Email : [email protected] Slideshare : www.slideshare.net/platico_dev