移从红宝石散列

Question

特定匹配的键值对我有一个Ruby散列：

@tags = { "project_status" => { "title" => "Project status" }, 
      "milestones"  => { "title" => "Milestones"}, 
      "lessons"  => { "title" => "Lessons"}, 
      "tasks"   => { "title" => "Tasks"} } 

我想shift特定键值对出该散列的。 例如如果我感兴趣的"milestones"标签，然后哈希shift会给我：

=> ["milestones", {"title"=>"Milestones"}] 

这就是我想要的东西。

除了，我不能找出如何选择一个特定的键值对。

我可以写的东西通过哈希迭代，直到我找到了匹配的密钥，然后调用shift，但我假设有一个更清洁的“红宝石的方式”来做到这一点:)

Answer 1

delete可能就是你正在寻找。它消除了从散列相应的键（而shift删除数组项），用于此:)

tags = { "project_status" => { "title" => "Project status" }, 
      "milestones"  => { "title" => "Milestones"}, 
      "lessons"  => { "title" => "Lessons"}, 
      "tasks"   => { "title" => "Tasks"} } 

def shift hash, key 
    [key, hash.delete(key)] # removes key/value pair 
    # [key, hash[key]] # leaves key/value pair 
end   

shift tags, 'milestones' # => ["milestones", {"title"=>"Milestones"}] 
tags # => {"project_status"=>{"title"=>"Project status"}, "lessons"=>{"title"=>"Lessons"}, "tasks"=>{"title"=>"Tasks"}}