From: KDr2 <kdr2@...>
Date: 2009-04-29T15:19:33+09:00
Subject: Re: Hash#map

--001636e8ff9dfae8900468ab8fd9
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit

irb(main):041:0> o={"a",1,"b",2}
=> {"a"=>1, "b"=>2}
irb(main):042:0> o.merge(o){|k,ov|ov*2}
=> {"a"=>2, "b"=>4}


On Wed, Apr 29, 2009 at 2:00 PM, Fredrik <fredjoha@gmail.com> wrote:

> Is there any good reason why Hash#map does not give back a Hash (Ruby
> 1.8 but same in 1.9 as far as I know)? I often find myself writing
> these kind of things:
>
> newhash = oldhash.inject({}) { |h,(k,v)| h[k] = some_operation(v); h }
>
> but that doesn't look pretty at all in my opinion. I want to just
> write like this:
>
> newhash = oldhash.map { |k,v| some_operation(v) }
>
> I finally got around to change this behaviour for my own code, but are
> all Ruby users supposed to invent this wheel on their own? Wouldn't it
> be better if Hash#map behaved like this? Or is there something I am
> missing?
>
> class Hash
>  def hashmap
>    self.inject({}) do |newhash, (k,v)|
>      newhash[k] = yield(k, v)
>      newhash
>    end
>  end
> end
>
>
> Regards,
> Fredrik
>
>


-- 
Best Regards,
   -- KDr2, at x-macro.com.

--001636e8ff9dfae8900468ab8fd9--