templater_dsl.rb

# A suggestion for an improved DSL for templater. The idea is to unify a lot of concepts and make
# them simpler.
#
# * Options and arguments are unified into 'argument', that can have an optional position
# * Templates, Files, EmptyDirectories, Directories and Invocations are unified into Recipes
# * A use_recipe function which can be used to pick and choose certain recipes
# * A simple block syntax for opening up generators and adding stuff to them
#
Rails.generator(:model) do

  # We can provide modules with some helpful functionality for building common types of generators
  # A very nice way of doing this, since it's flexible and doesn't depend on load order.
  # The end user of the generator will never see this, as it happens inside the framework
  include Rails::Generators::BaseGenerator
  include Rails::Generators::NamedGenerator

  ## ARGUMENTS

  # this argument is required and it can be given as a positional argument
  # the generator could be invoked like this:
  #     script/generate model --name User
  #     script/generate model User
  argument :name do |arg|
    arg.position = 0
    arg.description = "Name of the generator"
    arg.required = true
    arg.validate do |name|
      name !~ /\s/
    end
    arg.filter do |name|
      name.camel_case
    end
  end

  # this argument is not required and it cannot be given as a positional argument
  #     script/generate model --name User --no-migration
  argument :no_migration do |arg|
    arg.boolean = true
  end

  ## RECIPES

  recipe :model do
    template "app/models/%file_name%.rb" # will copy the template, interpolationg %file_name% into the destination
  end

  recipe :spec do
    directory 'spec' # will add all files in the directory 'spec' as templates
  end
  use_recipe :spec, :if => { :test_framework => :rspec }

  recipe :test_unit do
    template "test/models/model_test.rb", "test/models/#{file_name}_test.rb"
  end
  use_recipe :test_unit, :if => { :test_framework => :test_unit }

  recipe :monkey do
    template "test/monkey.rb"
  end
  use_recipe :monkey, false # do not use the monkey recipe
  use_recipe :monkey, true # no, we changed our minds, use it!
  use_recipe :monkey, :unless => { :monkey => 'Peter' } # use monkey recipe unless #monkey returns 'Peter'
  use_recipe :monkey, :unless => :peter? # use monkey recipe unless #peter? returns true

  recipe :migration do
    generate :migration, "add_#{file_name}", :table_name => file_name.pluralize
  end
  use_recipe :migration, :unless => :no_migration?

  recipe :add_route, :revertable => false do
    append_text "\n\n  resources :#{name}\n", :after => "Merb::Router.prepare do", :to => 'config/routes.rb'
  end

  ## METHODS
  
  # this is just a class so we can happily add methods to it
  def monkey
    "Peter"
  end

  def peter?
    monkey == "Peter"
  end

  def file_name
    name.snake_case
  end

  def class_name
    name.camel_case
  end
end

# We can use it like this in our code.
Rais.generator(:model).generate!(:name => "User", :recipes => [:model, :spec])