From: Robert Klemme <shortcutter@...>
Date: 2007-09-19T06:55:03+09:00
Subject: Re: Modifying a hash key

On 18.09.2007 20:05, Alex Shulgin wrote:
> On Sep 17, 10:41 pm, Robert Klemme <shortcut...@googlemail.com> wrote:
>> On 17.09.2007 20:19, Alex Shulgin wrote:
>>
>>>> I'd do this, note all the freezing in order to make errors with
>>>> changing keys obvious.
>>>> state = Hash.new {|h,k| h[k]=[]}
>>>> prefix = [].freeze
>>>> ARGF.each do |line|
>>>>   line.scan /\w+/ do |word|
>>>>     state[prefix] << word.freeze
>>>>     (prefix += [word]).freeze
>>>>     # or: prefix = (prefix.dup << word).freeze
>>>>   end
>>>> end
>>> Uh-oh...  this freeze stuff seems overly complicated to me.
>> Well, it's not necessary - I just put it there in order to find bugs.
>>
> [snip]
>> You find my code "overly complicated"?  Amazing...
> 
> Oh, sorry, I didn't want to hurt anyone...

Not hurt, just astonished. :-)

> First of all your and mine code do different things

Yes and no: your code does more but as far as I can see the gathering 
does basically the same in different ways.

>, and most
> importantly that freeze stuff _really_ scared me.  I thought it was
> some kind of garbage-collection voodoo. ;-)

No, it just prevents changing an instance.  #freeze has nothing to do 
with GC (unless you count not being able to overwrite a reference to an 
instance with a reference to nil).

> Now I see it may be safely removed after debugging the code.  This way
> your code looks much better, thanks!

:-)

Cheers

	robert