From: Peter Zotov <whitequark@...>
Date: 2011-12-09T15:03:13+09:00
Subject: Re: How can I do h["foo"] += "bar" if h["foo"] does not exist?

Andrew S. писал 09.12.2011 09:58:
> Hi there,
>
> I have a hash with various keys and values that are strings.
>
> If the key exists, the following works: h["foo"] += "bar"
>
> But if the key does not exist, I get an error.
>
> Is it possible _in one statement_ to cover both the cases where the 
> key
> does exist (as above) AND the case where the key does not exist - and 
> in
> this situation I'd like the new key and value pair to be created in 
> the
> hash.
>
> Any help gratefully received!
>
>  - A

$ irb
ruby-1.9.3-p0 :001 > hash = Hash.new("")
  => {}
ruby-1.9.3-p0 :002 > hash[:a] = "test"
  => "test"
ruby-1.9.3-p0 :003 > hash[:a] += " - one"
  => "test - one"
ruby-1.9.3-p0 :004 > hash[:b] += "nothing - two"
  => "nothing - two"
ruby-1.9.3-p0 :005 > hash
  => {:a=>"test - one", :b=>"nothing - two"}

-- 
   WBR, Peter Zotov.