browser function used in my appscripts to target Safari or WebKit dynamically

browser.rb

#!/usr/bin/env ruby
# encoding: UTF-8
require 'appscript'

VALID_BROWSERS = %w[ WebKit Safari ]

# Used in my appscripts to target Safari or WebKit dynamically.
# Returns an Appscript::Application for one of these browsers following this priority:
# 1. is frontmost
# 2. is running and default
# 3. is running
# 4. is default
def browser
  processes = Appscript::app("System Events").processes
  target,   = VALID_BROWSERS & processes[Appscript.its.frontmost.eq(true)].short_name.get
  target  ||= begin
    default_browser  = VALID_BROWSERS & [%x(VERSIONER_PERL_PREFER_32_BIT=yes /usr/bin/perl -MMac::InternetConfig -le 'print +(GetICHelper "http")[1]').chomp]
    running_browsers = VALID_BROWSERS & processes.short_name.get
    (running_browsers & default_browser)[0] || running_browsers[0] || default_browser[0]
  end
  Appscript::app(target) if target
end

This is part of http://stdout.caiochassot.com/post/2969463643/writing-applescripts-that-dynamically-target-either