mategem command. Opens any rubygem or ruby library file in TextMate.

mategem

#!/usr/bin/env ruby
# mategem (bash command)

require 'rubygems'

gemname = ARGV[0]
paths = $:.to_a.dup
begin
  gem gemname
  new_paths = $:.to_a.dup - paths
  where = new_paths.last
rescue Gem::LoadError
  begin
    where = (
      File.exists?('gems/gemrc.yml') ?
        `gem which --config-file gems/gemrc.yml #{gemname}` :
        `gem which #{gemname}`
      ).chomp
  rescue LoadError
    warn "Can't find ruby library file or shared library #{gemname}"
    exit
  end
end
if match = where.match(/(.*\/gems\/[^\/]+)/)
  gemroot = match[1]
  exec "mate #{gemroot}"
else
  if File.exists?(where)
    exec "mate #{where}"
  else
    puts "Couldn't understand location: #{where}"
  end
end