From: "David A. Black" <dblack@...>
Date: 2008-05-14T00:16:36+09:00
Subject: Re: Updating all values in a Hash

Hi --

On Tue, 13 May 2008, Sandro Paganotti wrote:

> On Tue, May 13, 2008 at 2:20 PM, Paul Dugdale <p.dugdale@gmail.com> wrote:
>> Does anyone know a good way to update all values in a hash.
>>
>>  E.g. If I have a big hash with each element containing a string as a
>>  value, how can I make each string lower-case?
>>  --
>>  Posted via http://www.ruby-forum.com/.
>>
>>
>
> I found this way
>
> h = Hash.new
>
> def h.[](val)
>  super.downcase
> end
>
> h["ciao"] = "CIOOOO"
>
> puts h["ciao"]
> # cioooo

That's very resourceful (I'm fully in favor of extending individual
objects), but I'm afraid it doesn't really do what Paul wants. All it
does is downcase what you see when you do h[val]. But the actual value
doesn't change:

>> h = {}
=> {}
>> def h.[](val); super.downcase; end
=> nil
>> h["a"] = "ABC"
=> "ABC"
>> h["a"]             # This gives you downcased string.
=> "abc"
>> h.fetch("a")       # But this doesn't.
=> "ABC"
>> h.values           # Neither does this. 
=> ["ABC"]


I think also that Paul is dealing with a hash that already has some
values, so the iterative solutions might be better.


David

-- 
Rails training from David A. Black and Ruby Power and Light:
   INTRO TO RAILS         June 9-12            Berlin
   ADVANCING WITH RAILS   June 16-19           Berlin
   INTRO TO RAILS         June 24-27           London (Skills Matter)
See http://www.rubypal.com for details and updates!