总是看到returning，这到底是个什么东东，查了一下找到了源代码

A Ruby-ized realization of the K combinator, courtesy of Mikael Brockman.

ruby 代码

  
def foo
  returning values = [] do
    values << 'bar'
    values << 'baz'
  end
end

foo # => ['bar', 'baz']

def foo
  returning [] do |values|
    values << 'bar'
    values << 'baz'
  end
end

foo # => ['bar', 'baz']

# File vendor/rails/activesupport/lib/active_support/core_ext/object/misc.rb, line 22

   

    ruby 代码
   
   
22:   def returning(value)
23:     yield(value)
24:     value
25:   end

实际上就是把一个value放到一个block中做处理，处理完毕之后返回，就这么简单

资料来自 http://caboo.se/doc.html