From: "mame (Yusuke Endoh)" <mame@...>
Date: 2012-11-24T08:45:17+09:00
Subject: [ruby-core:49914] [ruby-trunk - Feature #5531] deep_value for dealing with nested hashes


Issue #5531 has been updated by mame (Yusuke Endoh).

Priority changed from Normal to Low
Target version set to next minor

matz expressed a negative opinion for similar proposal (in Japanese, #5550)

The original in Japanese:

> Hash������������key-value������������������������������value���������������Hash������������������������������(������������Hash���������������������������������)���������������������������������������������������������������

English translation:

> The essence of Hash is a key-value mapping.  I'm negative for adding a method that assumes that the value is a recursive hash, or a method that is useful only for a recursive hash.

-- 
Yusuke Endoh <mame@tsg.ne.jp>
----------------------------------------
Feature #5531: deep_value for dealing with nested hashes
https://bugs.ruby-lang.org/issues/5531#change-33673

Author: weexpectedTHIS (Kyle Peyton)
Status: Assigned
Priority: Low
Assignee: matz (Yukihiro Matsumoto)
Category: 
Target version: next minor


This feature request stems from dealing with nested hashes, like the params from a request often dealt with in web frameworks.

Conditional code often needs to be written with multiple logical ANDs in order to achieve what this simple function can:

class Hash
  def deep_value(*ks)
    if ks.size == 1
      return self[ks.shift]
    else
      val = ks.shift
      return (self[val].is_a?(Hash) ? self[val].deep_value(*ks) : nil)
    end
  end
  
  alias dv deep_value
end


deep_value (dv) will simply recurse over a hash given a set of indexes and return the value at the end.

Example:

> foo = {:bar => {:baz => 'blah'}}
> foo.dv(:bar, :baz)
-> 'blah'
> foo.dv(:cats)
-> nil



-- 
http://bugs.ruby-lang.org/