Using a class to define methods that examine the contents of a string

class_string_introspection.rb

class MyString
  attr_accessor :str

  def initialize str
    self.str = str
  end

  def consonants
    str.gsub /[aeiuo0-9]/i, ''
  end

  def vowels
    str.gsub /[^aieou]/i, ''
  end

  def capitols
    str.gsub /[^A-Z]/, ''
  end

  def lowercase
    str.gsub /[^a-z]/, ''
  end

  def numbers
    str.gsub /[^0-9]/, ''
  end
end

puts str = "f2fp2LOCBVXBn2ifcgpy"

mystr = MyString.new str

%w{consonants vowels capitols lowercase numbers}.each {|m| puts "#{m}: #{mystr.send m}"}