Ruby on Rails: String manipulation

require 'string_manipulation'

require 'digest/sha1'
module StringManipulation
 
  # Remove ALL unneccessary whitespaces from string
  #    "   hello   world   " #=> "hello world"
  def strip_all
    self.gsub(/ +/, ' ').strip.chomp
  end
 
  # Remove everything that is not a-z or 0-9 or space
  def strip_illegal
    self.gsub(/[^a-zA-Z0-9 ]/, '')
  end
 
  # Returns the basename of a file
  def strip_extention
    self.gsub(/(\.(.*))$/,'')
  end
 
  # Strips RAILS_ROOT/public from string
  def url_from_path
    self.gsub("#{RAILS_ROOT}/public", '')
  end
 
  # Strips RAILS_ROOT from string
  def root_from_path
    self.gsub("#{RAILS_ROOT}", '')
  end
 
  # Hashes a string with SHA1
  def hashed
    Digest::SHA1.hexdigest(self)
  end
 
  # Make a nice downcase keyword list as string, seperated by single spaces
  #    keyword_list("   My §$% KEY   wordlist   ") #=> "my key wordlist"
  def keywordlist
    self.strip_illegal.downcase.strip_all
  end
 
  # Checks if a string contains only numerical characters
  def numstring?
    self =~ /^\d+(\.\d+|\d*)$/
  end
 
end
 
class String
  include StringManipulation
end