From: Trans <transfire@...>
Date: 2007-12-19T10:29:25+09:00
Subject: Re: Hash#collate



On Dec 18, 7:05 pm, Phrogz <phr...@mac.com> wrote:
> I wanted a method like Hash#update, but that preserved the values from
> both the original and argument Hash. A little searching failed to find
> it. (I did find that someone somewhere wrote a Hash#collate that's in
> my ri docs, but who knows where it came from. Its description appears
> not to do at all what I wanted, anyhow.)

That's from Facets, probably. But the latest version of Facets renamed
it to #mash, for "map hash", which is more descriptive of what it
does. (#collate remains an alias for the time being).

I like your definition --actually I'm surprised I haven't worked this
functionality into Facets yet. I guess I thought #weave took care of
it, but that's slightly different b/c it only combines arrays if the
value is already an array. So I'm going to add this to Facets. A
couple thoughts though...

The options don't feel quite right. Maybe it would more versatile to
define #uniq on Hash? So then

  { :a=>1, :b=>2 }.collate( { :a=>1, :b=>3 } ).uniq
  #=> { :a=>[1], :b=>[2,3] }

As for preserving the arrays, I'm not sure. Is that really all that
useful? Well, if it is it seems like a better definition for Hash#zip.

T.