Undefined local variable for hash in method ruby

Question

for some reason I\'m getting

NameError: undefined local variable or method `states\' for main:Object

though states is clearly defined. What

Answer 1

states is a local variable (because it starts with a lowercase letter). Local variables are local to the scope they are defined in (that's why they are called local variables, after all). So, states is defined in the scope of the script, but not in the scope of the method describe_state.

Method scopes don't nest, the only scopes that do nest are block scopes, so you would need to use a block. Thankfully, there is a method called define_method which creates a method from a block:

states = {
  CA: 'California',
  FL: 'Florida',
  MI: 'Michigan',
  NY: 'New York',
  OR: 'Oregon',
}

states[:CO] = 'Colorado'
states[:HI] = 'Hawaii'

cities = {
  CA: ['Alameda', 'Apple Valley', 'Exeter'],
  FL: ['Exeter', 'Amelia Island', 'Bunnell'],
  MI: ['Ann Arbor', 'East China', 'Elberta'],
  NY: ['Angelica', 'Apalachin', 'Canadice'],
  OR: ['Amity', 'Boring', 'Camas Valley'],
  CO: ['Blanca', 'Crestone', 'Dillon', 'Fairplay'],
  HI: ['Kailua', 'Hoopili', 'Honolulu'],
}

define_method(:describe_state) do |state|
  "#{state} is for #{states[state]}. " \
  "It has #{cities[state].length} major cities: #{cities[state].join(', ')}"
end

puts describe_state :CA
#=> CA is for California. It has 3 major cities: Alameda, Apple Valley, Exeter