migration_eg.rb

class CreateMedications < ActiveRecord::Migration
  def self.up
    create_table :medications do |t| 
      t.string  :name
      t.string  :prescriber
      t.date    :dispense_date
      t.integer :quantity
      t.integer :days_supply
      t.boolean :imported, :default => false
      t.boolean  :stopped, :default => false
      t.timestamps
    end 
  end 

  def self.down
    drop_table :medications
  end 
end

model_eg.rb

class Medication < ActiveRecord::Base

end

@medication = Medication.first
@medication.name = "Prozac"
@medication.save

@medication.potency
# --> NoMethodError: undefined method `potency' for #<Medication:0x103926db0>

@medication = Medication.find_by_name("Prozac")

proactive_dynamic_dispatch.rb

class Foo

  ["hello","goodbye","howdy"].each do |word|
    eval <<-END
      def say_#{word}
        puts "#{word}"
      end
    END
  end

end

f = Foo.new
f.say_hello
# --> Hello

reactive_dynamic_dispatch.rb

class Foo

  def method_missing(method_name)
    if method_name.to_s =~ /^say_([a-z]+)$/
      puts $1
    else
      super
    end
  end

end

f = Foo.new
f.say_bonjour
# --> bonjour

ruby_demo.rb

sum = 1 + 1
sum.class # => Fixnum

array = [1,2,3]
array << 4
array = 5

symbol = :foo

hash = {:arg1 => "val1", :arg2 => "val2"}
hash[:arg3] = "val3"

@instance_variable = "string"

def my_method(arg1)
  puts arg1
end

sinatra_eg.rb

require 'rubygems'
require 'sinatra'

get '/' do
  "Welcome to the index page"
end

style.sass

html
  background: #ccc
  
  body
    width: 960px
    margin: 0 auto
    background: #fff

    h1, h2
      font-size: 18px
    
    p
      a
        color: red
        &:hover
          color: purple