Rubyconf Bangladesh 2017 - Lets start coding in Ruby

I’m
Muntasim Ahmed
Developer @globo
ishkul.com
https://github.com/amuntasim/
https://www.linkedin.com/in/muntasim/

#include <stdio.h>
int main(){
printf(“I love C!”) /*seriously!!*/
return 0;
}

public class BigBrother{
public static void main(String[] args) {
String msg=“Hello!! Here is your big brother”
System.out.println(msg);
}
}

puts “its really simple! ”
class RubyClass
attr_accessor :v1, :v2
end
r = RubyClass.new
r.v1 = “test”
r.v1 => ‘test’
r.v2 => nil

Ruby Philosophie
“I believe people want to express themselves
when they program. They don’t want to fight
with the language. Programming languages
must feel natural to programmers. I tried to
make people enjoy programming and
concentrate on the fun and creative part of
programming when they use Ruby.”
-- Yukihiro "Matz" Matsumoto, Ruby creator

Why Ruby?
• Its simple
• Easy to write/learn
• Truly object oriented
• Emphasize programming speed!
• Less code, fewer bugs
• Open source

From where to start?!
Installation
• Just google with install ruby with
rvm/rbenv in <Your OS>
• Should be simple as like Ruby 

From where to start?!
IRB = Interactive Ruby
> Irb
Or
tryruby.org

Everything is an object
3.odd? => true
“string”.length => 6
[].empty? => true
“abc”.methods => [..,..,..]

It doesn’t mind
• if you don’t like ‘;’ at the end
• even a method without ()
• If you want to express in your way
• and many more..
Happy Programmer 

Variables
• Any plain, lowercase word
• a, my_variable and rubyconf2017
• > a => undefined local variable or method `a`
• > a = ‘hello’ => hello
• > a => hello
• > a = 1 => 1 

Number
• Integers (Fixnum), Float
• 1, -3002, 2.3, 1233.1e12
• > 1.class => Fixnum
• >1.3.class => Float
• >1.3e12.class => Float
• >1 + 2 => 3
• >1.4+ 4 => 5.4

Strings
• Anything surrounded by quotes ‘’ or “”
• ‘RubyConf 2017’, “Muntasim”
• > a = ‘hello’ => hello
• > a => hello
• > a.upcase => HELLO
• > a.upcase.object_id => 2212289940
• > a.object_id => 2212352200
• > a << ‘ world’ => hello world

Symbols
• Start with a colon, look like words
• Uses same object reference
• Useful for keys
• :test, :a
• >"test".object_id => 2212252220
• >"test".object_id => 2212236940
• > :test.object_id => 196968
• > :test.object_id => 196968

Constants
• variables, starts with a capital
• Foo, Conf_Date
• :test, :a
 Foo = ‘bar’ => bar
 Foo = ‘dum’ =>’dum’ #warning.
 if something == Foo
#do something
end

Methods
def hi
puts ‘Hi there!’
end
 hi => Hi there!
def hello(name)
puts “Hello #{name}!”
end
 hello ‘khoka’ => ‘Hi khoka!’

Arrays
• A list surrounded by square brackets
• [1,2,4]
• [‘a’, ‘B’, 1] 
 a = [1,3,5,’7’, ‘e’] => [1,3,5,’7’, ‘e’]
 a[2] => 3
 b = [5,6] => [5,6]
 a+b => [1,3,5,’7’, ‘e’, 5,6]
 ….

Hashes
• A list surrounded by curly braces
• {:a => 2, b: ‘3’}
 a = {:a => 2, b: ‘3’} => {:a => 2, b: ‘3’}
 a[:a] => 2, a[:b] => ‘3’
 a.keys => [:a, :b]
 ….

Classes
class Car
attr_accessor :wheels, :color
end
 c = Car.new => #<Car:0x00000107b09840>
 c2 = Car.new =>#<Car:0x00000107b00a60>
 c.color = ‘white’ => white
 c.color => white
 c2.color => nil

class Car
attr_accessor :wheels, :color
def initialize(wheels, color)
self. wheels = wheels
self. color = color
end
def color_and_wheels
“#{color} color with #{wheels} ‘wheels’)”
end
end
 c = Car.new(4, ‘white’) => #<Car0x00000b09840 .....>
 c.color_and_wheels => ‘white color with 4 wheels’

Classes (Open to modify)
class Bird
def make_sound
p “ka-ka-ka”
end
def color
p “black”
end
end
b = Bird.new
b.make_sound => ‘ka-ka-ka’
b.color => ‘black’

Classes (Open to modify)
class Bird
def make_sound
p “kuhu :D ”
end
def name
p “a name”
end
b = Bird.new
b.make_sound => ‘kuhu :D’
b.color => ‘black’
b.name => ‘a name’
Don’t like the sound? Just open the class and
modify it

Module
 Like classes, modules contain methods and
constants but don’t have instances.
 encourage modular design
 Ruby doesn’t support multiple inheritance
but can have that behavior by modules

Module
module M
def m1
end
end
module M
class C
end
end
M.new c = M::C.new

Module
class Thing < Parent
include MathFunctions
include Taggable
include Persistence
end

module Feature
def feature1
p ‘feature1’
end
def feature2
p ‘feature2’
end
end
module Habits
def habit1
p ‘habit1’
end
def habit2
p ‘habit2’
end
end
class Parent
def a1
p ‘a1’
end
end
class Thing < Parent
include Feature
include Habits
end
t = Thing.new
t.a1 => ‘a1’
t.feature1 => ‘feature1’
t.habit2 => ‘habit2’

More on Ruby Basics
• http://rubymonk.com/
• http://tryruby.org/
• http://rubykoans.com/
• http://ruby.learncodethehardway.org/
• http://poignant.guide/ (funny!)

Ruby eco system
• RVM/rbenv
• RubyGems
• Bundler
• Git/github

Ruby vs Ruby on Rails(aka Rails)
• Rails is written in the Ruby
• Rails uses many Ruby gems
• Rails is a framework
• Rails is used to build web apps
rubyonrails.org

Editors
• RubyMine
• Sublime Text
• Textmate
• Vim
• Emacs
• Or whatever you like

References:
• https://www.ruby-lang.org/en/
• https://dzone.com/refcardz/essential-ruby
• http://www.jasimabasheer.com/posts/meta_i
ntroduction_to_ruby.html
• http://curriculum.railsbridge.org/docs/

Rubyconf Bangladesh 2017 - Lets start coding in Ruby

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