Examples of code with comments for https://twitter.com/avdi/status/256820958676013056

interpol_rakefile.rb

# From: https://github.com/seomoz/interpol/blob/5108f29eadf52c4401785d86f4bc75f590813792/Rakefile#L42-51

desc "Import the twitter bootstrap assets from the compass_twitter_bootstrap gem"
task :import_bootstrap_assets do
  # when the gem installed as a :git gem, it has "-" as a separator;
  # when it's installed as a released rubygem, it has "_" as a separator.
  gem_lib_path = $LOAD_PATH.grep(/compass[-_]twitter[-_]bootstrap/).first
  assets = Dir[File.join(gem_lib_path, '..', 'vendor', 'assets', '**')]

  destination_path = File.expand_path("../lib/interpol/documentation_app/public", __FILE__)
  FileUtils.cp_r(assets, destination_path)
end

rspec_mocks_stub_const.rb

# From: https://github.com/rspec/rspec-mocks/blob/68f1d1c1bacad919a5528014da03f76b7165eabc/lib/rspec/mocks/stub_const.rb#L7-57

# We only want to consider constants that are defined directly on a
# particular module, and not include top-level/inherited constants.
# Unfortunately, the constant API changed between 1.8 and 1.9, so
# we need to conditionally define methods to ignore the top-level/inherited
# constants.
#
# Given:
#   class A; B = 1; end
#   class C < A; end
#
# On 1.8:
#   - C.const_get("Hash") # => ::Hash
#   - C.const_defined?("Hash") # => false
#   - C.constants # => ["B"]
#   - None of these methods accept the extra `inherit` argument
# On 1.9:
#   - C.const_get("Hash") # => ::Hash
#   - C.const_defined?("Hash") # => true
#   - C.const_get("Hash", false) # => raises NameError
#   - C.const_defined?("Hash", false) # => false
#   - C.constants # => [:B]
#   - C.constants(false) #=> []
if Module.method(:const_defined?).arity == 1
  def const_defined_on?(mod, const_name)
    mod.const_defined?(const_name)
  end

  def get_const_defined_on(mod, const_name)
    if const_defined_on?(mod, const_name)
      return mod.const_get(const_name)
    end

    raise NameError, "uninitialized constant #{mod.name}::#{const_name}"
  end

  def constants_defined_on(mod)
    mod.constants.select { |c| const_defined_on?(mod, c) }
  end
else
  def const_defined_on?(mod, const_name)
    mod.const_defined?(const_name, false)
  end

  def get_const_defined_on(mod, const_name)
    mod.const_get(const_name, false)
  end

  def constants_defined_on(mod)
    mod.constants(false)
  end
end

vcr_hooks.rb

# From: https://github.com/myronmarston/vcr/blob/v2.2.5/lib/vcr/util/hooks.rb#L48-60

module ClassMethods
  def define_hook(hook_type, prepend = false)
    placement_method = prepend ? :unshift : :<< 

    # Put the hook methods in a module so we can override and super to these methods.
    self::DefinedHooks.module_eval do
      define_method hook_type do |*filters, &hook|
        hooks[hook_type].send(placement_method, FilteredHook.new(hook, filters))
      end 
    end 
  end 
end