A script that opens any gem in your EDITOR.

dive.rb

#!/usr/bin/env ruby
# USAGE: dive GEM_NAME
#
# Opens the lib/ directory of the specified gem in EDITOR. If you're in a Bundler
# project, it will open the locked-down version of the gem.
#
# You can supply only the first few letters of the gem, and the first gem that
# matches will be opened.


class Dive
  def initialize(gem_name)
    @gem_name = gem_name
  end

  def call
    gem = find_gem
    gem_lib_path = File.join(gem.full_gem_path, "lib")
    open(gem_lib_path)
  end

  private

  def find_gem
    gem = gems.find { |gem| gem.name.start_with?(@gem_name) }
    gem or fail
  end

  def gems
    require "bundler"
    Bundler.environment.specs | Gem::Specification.to_a
  rescue Bundler::GemfileNotFound
    Gem::Specification.to_a
  end

  def open(dir)
    Dir.chdir(dir) do
      system ENV["EDITOR"], dir
    end
  end

  def fail
    warn "Gem not found: #{@gem_name}"
    exit
  end
end

Dive.new(ARGV.first).call