From: Rob Biedenharn <Rob@...>
Date: 2010-03-25T21:10:57+09:00
Subject: Re: hash problem

On Mar 25, 2010, at 6:16 AM, Adam Nelreth wrote:
> Ok - here is code:
>
> login = 'aaa'
> test = Hash.new

You can still simplify this with the suggestion that you received from  
several others.  Initialize your hash as:

test = Hash.new(0)

So that missing keys will appear as 0. (see note at end, too)

>
> imap = Net::IMAP.new('imap-server',993,true)
> puts "passwd: "
> pass = gets.chop
> imap.login(login,pass)
> imap.select('example')
> imap.uid_search(["SUBJECT", "To-check",
>                 "NOT", "SEEN"]).each do |uid|
>        mess = imap.uid_fetch(uid, "ENVELOPE")[0].attr["ENVELOPE"]
>        title = mess.subject
>        ip =
> /(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4] 
> [0-9]|[01]?[0-9][0-9]?)/.match(title)
>        if test.has_key?(ip)
>                test[ip] += 1
>        else
>                test[ip] = 1
>        end

Then you don't need to have this if, just put: (including where Robert  
pointed out that ip holds a MatchData object.

                  test[ip[0]] += 1

Which is syntactic sugar for:
                  test[ip[0]] = test[ip[0]] + 1

If that key (ip[0]) doesn't exist, it behaves like
                  test[ip[0]] = 0 + 1

> end
> imap.logout()
> imap.disconnect()
>
> I try with else test[ip] = 1 and without else - it still doesn't work
> like I need - maybe there is problem with "" or '' because I don't set
> it when I put key to hash table
> -- 
> Posted via http://www.ruby-forum.com/.
>


-Rob

*Note: In general, if you want to set up a hash this way, you might  
need to specifically assign to the hash like:

   test = Hash.new {|h,k| h[k] = 0 }

but a Fixnum is immutable so there's no problem "sharing" the value  
0.  If you were adding to an Array, these two initializations would  
lead to different results:

   test = Hash.new([])
   test = Hash.new {|h,k| h[k] = [] }

(What those results *are* is left as an exercise for the reader ;-)


Rob Biedenharn		http://agileconsultingllc.com
Rob@AgileConsultingLLC.com