From: Florian Gross <flgr@...>
Date: 2004-11-03T08:08:48+09:00
Subject: Re: Converting hash keys to symbols

Jamis Buck wrote:

> Is there an elegant way of converting all of the keys of a hash to a 
> symbol? The solution can assume that the existing keys are either 
> strings or symbols. 

Does this help?

a = Hash.new do |hash, key|
   hash.fetch(key.is_a?(Symbol) ? key.to_s : key.to_sym, nil)
end

a["one"] = "eins"
a[:two] = "zwei"

a["one"] == a[:one] # => true
a["two"] == a[:two] # => true

> Also, if a key is a string, it may contain a dash 
> character which must be converted to an underscore.

Why? Symbols can contain dash characters. See :"foo-bar", %s{foo-bar}, 
"foo-bar".intern and "foo-bar".to_sym.

Also note that #to_sym is defined for Symbol as well.

So maybe you could also do something like this (in case the above 
doesn't work for you):

result = Hash.new(&a.default_proc)
until a.empty?
   key, value = *a.shift
   result[key.to_sym] = value
end
a.replace(result)