Stephen Lloyd

Websites

• www.ruby-lang.org
• www.ruby-doc.org
• www.apidock.com/ruby
• Make even better Ruby best-ruby.com

Debug

• = debug @post
• = local_variables.inspect
  = instance_variables.inspect
• obj.private_methods
  obj.public_methods
  obj.protected_methods
  obj.singleton_methods
• MyClass.private_instance_methods
  MyClass.protected_instance_methods
  MyClass.public_instance_methods
• obj.public_methods.sort
  Can make review easier too.
• The equivalent of cfdump #{@listing.inspect}
• raise "something in quotes'
  raise a_variable
• flash[:notice]
  flash[:error]
  flash[:failure]
  flash[:success]
• Rails.logger.info "stuff"
  
• logger.info "#$%#$%#$%&@#$%@$%&#@^& This is my message"
• rescue => e
  render :text => " #{e.message}"

rails c

in the model/agent.rb file, there is the Agent class, so

irb> Agent.methods
irb> Agent.find('c5a98f8f-09d9-4581-9b26-acc033e7610e')
irb> Agent.find('jeff-green')

Resources

• string functions in ruby
• guides.rubyonrails.org/ debugging_rails_applications

A Hash is an Associative Array

Puts vs Print

• n=["a","b","c","d","e"]
  puts n.last(2)
  d
  e
  
  print n.last(2)
  ["d","e"]

Shuffle

• n.shuffle creates a random order of the array

Unique

• Use the uniq method to return only the non-repeated values
• How many unique values? n.uniq.length

Reverse

• puts ('a'..'z').to_a.reverse.join
• the range is converted to an array, reversed, and converted to a string.
• it outputs zyxwvutsrqponmlkjihfedcba
• to_s converts an array to a string (in list form, comma delimited)

Arrays

• Array syntax: groceries = ['kiwis', 'cereal', 'milk'] also can be done this way: groceries = %w{hot mild cold}
• 0-based. groceries[1] is cereal
• A negative number counts back from the end, starting with -1. groceries[-3] is kiwis
• to create a blank array: groceries = Array.new

Multi-dimentional Arrays

• colors = [ ['Red', 'Green', 'Blue'] , ['Cyan', 'Magenta', 'Yellow'] ]
• colors[1][2] is Blue, colors[2][0] is Cyan

• Everything in Ruby is an object
• Variable names are case sensitive
• Methods that end with a ? return true or false. Methods that end with ! alter the value of the object.
• integer type is Fixnum. floating point is Float. numbers are Numeric
• parallel assignment: x,y = 1,2
• multiple assignment: x=y=z=2
• 20 / 7 = 2
• 20.0 / 7 = 2.8571...
• 20 % 7 = 6 ( the remainder of a division )
• 3 **3 = 9 (3 to the power of 3)
• rand 100 or rand(100) will generate 0-99, never 100.
  • use rand(100) + 1 to generate 1-100
  • use rand(101) to generate 0-100
• 101.even? will return false
• + concatenates Strings. << updates the variable with new content at the end.
  msg = 'world'
  msg << '!'
  puts msg
  world!
• msg.object_id - every object has an id
• qty = 5
  puts "the number you chose was #{qty}" (must be in double quotes to work)
• to concatenate numbers in strings, they must be converted to strings. "The value of x: " + x.to_s
• use %q{thius is "my" string} to create a multi-line string where you don't have to worry about escaping quotes.
• A Symbol is assigned with a colon. car = :Toyota, priority = :high
• Constants begin with a Capital letter, but by convention, they are written in all caps. DOZEN = 12
• Dates and Times. Time.now, Time.now.year, Time.now + 60 adds 60 seconds

• Ruby IDE's: SciTE, Netbeans
• ruby 2getland.rb runs the program. ruby -w 2getland.rb runs it and shows warnings
• puts is the most common output method. It automatically adds a new line at the end.
  print does not add a new line at the end.
• \n in the output string within quotes adds a new line. \a adds a beep \t tab, \" quotes, \\ backslash, \r return
  \' only escapes ' when used inside single quotes
• gets() asks for input and always returnsa string type
  • if you want to use the results of the gets as numeric, it must be converted.
    age = gets()
    ageNum = age.chomp.to_i
• # is a comment

• The Interactive Ruby window accepts simple commands like 2+2
• To use the command prompt, use the launcher in the start menu: Start Command Prompt with Ruby.
  Then, Ruby --version will work. Oddly, 2+2 does not.
• in the Start Command Prompt with Ruby shell: Ruby 1helloworld.rb
• Use puts with double quotes to evaluate ruby commands within curly brackets. puts "Hello #{name}"
• \a in the puts or print string adds a beep(alert) in the progam

puts / print

• puts adds a new line at the end.
• print does not. example: print "This land is " print "#{pnoun}" print " land"