module Rails::Generators::Actions

end
%(config.asset_host = "localhost:3000")
environment(nil, env: "development") do

end
%(config.asset_host = "cdn.provider.com")
environment do

The code can also be specified as the return value of the block:

corresponding file in +config/environments+.
+:env+ can also be an array. In which case, the code is added to each

end
# ...
config.asset_host = "localhost:3000"
Rails.application.configure do
# config/environments/development.rb

Results in:

environment %(config.asset_host = "localhost:3000"), env: "development"

corresponding file in +config/environments+ instead.
If the +:env+ option is specified, the code will be added to the

end
# ...
config.asset_host = "cdn.provider.com"
class Application < Rails::Application
# config/application.rb

Results in:

environment %(config.asset_host = "cdn.provider.com")

+config/application.rb+ so that it applies to all environments.
By default, adds code inside the +Application+ class in

Adds configuration code to a Rails runtime environment.

def environment(data = nil, options = {})
  sentinel = "class Application < Rails::Application\n"
  env_file_sentinel = "Rails.application.configure do\n"
  data ||= yield if block_given?
  in_root do
    if options[:env].nil?
      inject_into_file "config/application.rb", optimize_indentation(data, 4), after: sentinel, verbose: false
    else
      Array(options[:env]).each do |env|
        inject_into_file "config/environments/#{env}.rb", optimize_indentation(data, 2), after: env_file_sentinel, verbose: false
      end
    end
  end
end