From: Trans <transfire@...>
Date: 2008-04-13T19:04:23+09:00
Subject: Re: Hash#slice



On Apr 13, 4:58 am, "Robert Dober" <robert.do...@gmail.com> wrote:
> On Sun, Apr 13, 2008 at 2:51 AM, ara.t.howard <ara.t.how...@gmail.com> wrote:
>
> >  On Apr 12, 2008, at 5:12 PM, Trans wrote:
>
> > > Let see.... Facets:
>
> > >  class Hash
>
> > >   # Returns a new hash with only the given keys.
>
> > >   def slice(*keep_keys)
> > >     h = {}
> > >     keep_keys.each do |key|
> > >       h[key] = fetch(key)
> > >     end
> > >     h
> > >   end
>
> > >   # Replaces hash with a new hash having only the given keys.
> > >   # This return the hash of keys removed.
>
> > >   def slice!(*keep_keys)
> > >     removed = except(*keep_keys)
> > >     replace(slice(*keep_keys))
> > >     removed
> > >   end
>
> > >  end
>
> >  okay, you should add the block form ;-)
>
> >  headers.slice{|k,| k =~ %r/^HTTP_/}
>
> >  handy.....
>
> >  cheers.
>
> >  a @http://codeforpeople.com/
> >  --
> >  we can deny everything, except that we have the possibility of being
> > better. simply reflect on that.
> >  h.h. the 14th dalai lama
>
> Hmm maybe it is a more consistent approach not to add a block to slice.
>
> FWIAC, I use hselect, kselect and vselect, the simplified code
> goes like this (1) of course
>   def kselect  &blk
>       hselect{ |k,| blk.call(k) }
>   end
>
>   def vselect &blk
>       hselect{ |_,v| blk.call(v) }
>   end
>   def hselect &blk
>      #almost Tom's code of course
>   end

Why not?

  hash.keys.select
  hash.values.select

> You might write
>   h.slice(*[*1..10]){|k,v| whatever k, v }
> which indeed I like
>
> I would write
>    h.slice(*[*1..10]).hselect{|k,v| whatever k, v}
> which indeed I like less, *but* I dislike the inconsistency of #select now.
>
> The ideal solution might be to add a block to Enumerator#select too,
> what about that?

Hmm... I don't understand Enumerator#select comes from
Enumerable#select and already takes a block.

T.