Ruby Scoping

01a_conditionals.rb

#####################
# CONDITIONALS
#####################

def variables_in_passing_conditionals
  special_string = "Awesome!"

  if true
    result = "You win!"
  end

  "#{result}, #{special_string}"
end

variables_in_passing_conditionals

01b_conditionals.rb

#####################
# CONDITIONALS
#####################

def variables_in_failing_conditionals
  special_string = "Awesome!"

  if false
    result = "You win!"
  end

  "#{result}, #{special_string}"
end

variables_in_failing_conditionals

02_global.rb

#####################
# GLOBAL
#####################

def testing_scope_global_variable(num)
  $a << num
end

$a = [1, 2]

testing_scope_global_variable(2)

$a

03_constants.rb

#####################
# CONSTANTS
#####################

MAX_AGE = 22

def working_with_constants
  "the max age for a student is: #{MAX_AGE}"
end

working_with_constants

MAX_AGE

04a_namespaced_constants.rb

##############################
# CONSTANT SPECIFIC NAMESPACE
##############################

def working_with_constants
  "the max age for a student is: #{Stuff::Max_age}"
end

module Stuff
  Max_age = 22
end

working_with_constants

04b_dynamic_constants.rb

#####################
# DYNAMIC CONSTANTS
#####################

MAX_AGE = 42

def working_with_constants
  MAX_AGE = 22
  "the max age for a student is: #{MAX_AGE}"
end

working_with_constants

MAX_AGE

04c_changing_a_constant.rb

############################
# CHANGING A CONSTANT
############################

MAX_AGE = 22

def working_with_constants
  "the max age for a student is: #{MAX_AGE}"
end

working_with_constants

MAX_AGE = 99

working_with_constants

05_locals.rb

#####################
# LOCAL SCOPE
#####################

def testing_scope_local_variable(num)
  a = []
  a << num
end

a = [1, 2]

testing_scope_local_variable(2)

a

06_internal_iterators.rb

#####################
# INTERNAL ITERATORS
#####################

def variables_with_loops
  1.upto(10) do |num|
    number = num
  end
  number
end

variables_with_loops

07_external_iterators.rb

#####################
# EXTERNAL ITERATORS
#####################

def variables_with_for_loops
  for num in (1..10)
    number = num
  end
  number
end

variables_with_for_loops

the weird part about constant in Rails is it can be changed. If you are in Rails, you can use CONSTANT = 'something'.freeze