为什么Rails4放弃了对Gemfile中“assets”组的支持 - Why did Rails4 drop support for “assets” group in the Gemfile

问题：

In Rails 3, gems used exclusively to generate assets in the asset pipeline were properly placed in the assets group of the Gemfile: 在Rails 3中，专门用于在资产管道中生成资产的gem被正确放置在Gemfile的assets组中：

...

# Gems used only for assets and not required
# in production environments by default.
group :assets do
  gem 'sass-rails'
  gem 'coffee-rails'
  gem 'uglifier'

  # See https://github.com/sstephenson/execjs#readme for more supported runtimes
  # gem 'therubyracer', :platforms => :ruby
end

Now, according to the (still in progress) upgrade documentation : 现在，根据（仍在进行中） 升级文档 ：

Rails 4.0 removed the assets group from Gemfile. Rails 4.0从Gemfile中删除了资产组。 You'd need to remove that line from your Gemfile when upgrading. 升级时，您需要从Gemfile中删除该行。

Sure enough, making a new project with RC1 yields a Gemfile with asset-related gems included by default outside of any group: 果然，使用RC1创建一个新项目会产生一个Gemfile，其默认包含在任何组之外的与资产相关的gems：

source 'https://rubygems.org'

# Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
gem 'rails', '4.0.0.rc1'

# Use sqlite3 as the database for Active Record
gem 'sqlite3'

# Use SCSS for stylesheets
gem 'sass-rails', '~> 4.0.0.rc1'

# Use Uglifier as compressor for JavaScript assets
gem 'uglifier', '>= 1.3.0'

# Use CoffeeScript for .js.coffee assets and views
gem 'coffee-rails', '~> 4.0.0'

# See https://github.com/sstephenson/execjs#readme for more supported runtimes
# gem 'therubyracer', platforms: :ruby

...

Does this mean these gems will now be bundled in production builds by default? 这是否意味着这些宝石现在默认捆绑在生产版本中？ If so, why the change of heart? 如果是这样，为什么改变心意？ Is Rails 4 moving towards the dynamic generation of assets in production? Rails 4是否正朝着生产中动态生成资产的方向发展？

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解决方案：

参考： https://stackoom.com/en/question/16q0C