my create gem script

create_gem.rb

#!/usr/bin/env ruby

def gem_name
  ARGV[0].chomp("/")
end

def constant_name
  constant_name = gem_name.split('_').map{|p| p[0..0].upcase + p[1..-1] }.join
  constant_name = constant_name.split('-').map{|q| q[0..0].upcase + q[1..-1] }.join('::') if constant_name =~ /-/
  constant_name
end

def constant_array
  constant_name.split('::')
end

def rvmrc
  "rvm 1.9.3\n"
end

def gem_name_spec
  str = ""
  str << "require \"spec_helper\"\n"
  str << "\n"
  constant_array[0..-2].each_with_index do |c,i|
    str << "  " * i
    str << "module " << c << "\n"
  end
  str << "  " * (constant_array.size - 1) << "describe " << constant_array.last << " do\n"
  str << "  " * constant_array.size << "it{ fail \"not implement yet.\" }\n"
  (constant_array.size - 1).downto(0) do |i|
    str << "  " * i << "end\n"
  end
  str
end

def gemfile_for_rspec
  str = ""
  str << "\n"
  str << "gem \"rake\"\n"
  str << "gem \"rspec\"\n"
  str
end

def rakefile_for_rspec
  str = ""
  str << "\n"
  str << "require \"rspec/core/rake_task\"\n"
  str << "RSpec::Core::RakeTask.new(:spec)\n"
  str << "task :default => :spec\n"
  str
end

def gemfile_for_guard
  str = ""
  str << "\n"
  str << "gem \"guard\", :require => false\n"
  str << "gem \"guard-rspec\", :require => false\n"
  str << "gem \"ruby_gntp\", :require => false\n"
  str
end

def travis
  "rvm: 1.9.3\n"
end

system "bundle gem #{gem_name}" # create base
Dir.chdir gem_name do
  # add rvm
  ## to rvmrc
  File.write(".rvmrc", rvmrc)

  # add rspec
  ## to Gemfile
  File.open("Gemfile", "a"){ |f| f << gemfile_for_rspec }
  ## to Rakefile
  File.open("Rakefile", "a"){ |f| f << rakefile_for_rspec }
  ## init
  system "bundle exec rspec --init"
  ## to spec directory
  File.write("spec/#{gem_name}_spec.rb", gem_name_spec)
  ## add 'require "gem_name"' to spec_helper
  File.write("spec/spec_helper.rb", "require \"#{gem_name}\"\n" << File.read("spec/spec_helper.rb"))

  # add guard
  ## to Gemfile
  File.open("Gemfile", "a"){ |f| f << gemfile_for_guard }
  ## init
  system "bundle exec guard init rspec"

  # add travis
  ## to travis.yml
  File.write(".travis.yml", travis)
end